C60+ predicted in 1987 to be a Diffuse Interstellar Band (DIB) carrier  and in 2015 four DIBS assigned unequivocally to C60+ by Maier’s group. The first time any identified in nearly 100 yrs! A brilliant achievement.


http://pubs.acs.org/doi/pdf/10.1021/acscentsci.5b00292  Final Maier Q+A

HWKroto-1987 discussing the possibility of C60 and its analogues in space and as DIB carriers

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Fantastico…Now the weaker two lines have been found spot on…so all four lines are confirmed and my 4/5 rule applies 4 out of 5 rule 4 out of 5 Stat

Jim Watson identified CH as the carrier an unusually narrow DIB which was much narrower than the  standard ones cf Binder1

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Fullerene Molecules in Space: C60, ions such as C60+, endohedral fullerenes M@C60, and analogues M…C60 etc almost certainly ionised and their possibility as carriers of the Diffuse Interstellar Bands, DIBs
1987 Prediction

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                              They seek it here, they seek it there,
                               they seek that magenta Buckyball everywhere,
                               but space is full of high energy photons too,
                               and so it is ionised and has changed its hue.


They forget that the diffuse clouds of space, where the carriers of the Diffuse Interstellar Bands reside, are bathed in up to 13.6 eV photons (the ionisation potential of the H atom) and so C60 will be ionised and have changed colour!

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 It’s official – C60+ is in Space, all over the Galaxy and almost certainly all over the Universe


Laboratory confirmation of C60+ as the carrier of two diffuse interstellar bands
E. K. Campbell, M.Holz, D. Gerlich & J. P. Maier


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This breakthrough opens up  highly exciting whole new fields of focused laboratory and astronomical studies to see whether any other fullerene analogues are carriers of other DIBs.  A significant number of C60 analogues must also be present in the ISM. It also yields important new data which impact significantly on our understanding of the chemistry of the ISM as well as the clouds in which stars and planets form.

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Analysis of why the C60+ Diffuse Interstellar Band (DIB) assignment is so scientifically convincing

It is quite important to realise that this is not just a simple case of assigning two DIB lines (observed in 1994 in the  near infrared based on the Basel groups initial 1993 laboratory study) but an elegant sequence of several step-by-step research observations over many years uncovering a series of several circumstantial scientific results ending with a perfect fit achieved by the Basel group. This makes the whole story so much more scientifically convincing, than if two lines been just had happened to fit!

1)  Detection of some unusual lines originally in 1919*  (Lick Observatory) but possibly earlier and shown to be interstellar in 1934.  These lines have intrigued astronomers and other scientists ever since and now some 400 are known

2)  Synthesis and spectroscopy of long carbon chain molecules (Sussex University 1974-78)

3)  Radioastronomy studies indicate carbon chains more abundant than expected in the ISM (NRC Canada/Sussex University 1975-78)

4)  Conjecture that the carbon chains could be responsible for the diffuse interstellar bands 1977 (NRC Canada)

5)  The chain molecules discovered flowing out from cool red giant carbon stars (Max Planck Bonn 1978)

6)  Laser carbon vaporisation simulation of the atmosphere of carbon star, a) to check the idea that the carbon chain molecules could be made in stars and b)  a pilot experiment to determine if the carbon chains are actually responsible for the DIB’s. The first experiment worked perfectly and showed carbon chains were easily made in a simulated stellar atmosphere. (Rice University/Sussex University 1985)

7) The second experiment was never carried out as the first experiment unexpectedly turned up the fact that an incredibly stable molecule self-assembled from a chaotic plasma in uniquely high abundance compared with anything else. (Rice University/Sussex University 1985)

8) This is the most important aspect of the C60 discovery by far and led to the suggestion that it might not be a coincidence but actually a clue perhaps to the carrier of the diffuse interstellar bands; almost certainly ionised as C60+ and/or as numerous possible C60 analogues 1987 (Sussex University 1987- )

9) C60 isolated 1990 making its detailed study possible (Arizona University/Heidelberg and Sussex University)

10)  The start of the last chapter was the critical experiment carried out by the Basel University group which observed two lines of C60+ in a Ne matrix at low temperature. These lines are of course shifted somewhat from the gas phase frequencies.  This study is arguably the most important one of the final phase of the C60+ detection because it stimulated an astrophysical search based on reliable laboratory measurements and two lines are much better than one  1993 (Basel University)

11)  The infrared region is now much more accessible and astronomers decided to carry out a search based on the Basel observations in this newly available part of the spectrum and found two lines in tantalisingly close agreement with the laboratory measurements taking into account matrix solid-state shifts.  Thus indicating gas phase study is vital for unequivocal assignment (ESA/Leiden University 1994)

12) The amazing Canadian discovery using Spitzer Satellite data that C60 is flowing out of stars indicated the hunt might soon be up 2010 (NASA/University of Western Ontario)

13)  The icing on the cake is a fantastic 20-year effort to develop state-of-the-art technology to obtain the gas phase spectrum of C60+ under conditions of very low temperature and pressure and find that they agree perfectly with the astronomers’ measurements (Basel University 2015)

*Takeshi Oka notes: The strongest DIB at 4430 is mentioned on page 288 of Volume 9-10-11 of the Henry Draper catalog published from 1911 to 1919. A. D. Code in Publ. Astron. Soc. Pac. 70, 404 (1958) examines the plate taken by Annie Jump Cannon and confirmed it. The plate is not dated and George Herbig (ApJ 196, 129, 1975) said “sometime between 1911 and 1919”. Others argue that the plate is much older and may even be of the late 19th century! (Cannon lived 1863-1941). In any case I think it is safe to say that it is more than 100 years since the first diffuse interstellar band was observed.

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Come in C60+ after nearly 100 years your number is finally up

The Basel group of John Maier has made an outstanding breakthrough in unequivocally assigning two diffuse interstellar bands to the ion C60+ and so has succeeded in identifying a species in space which has eluded astronomers and other scientists for nearly 100 years


The football team of the year  Basel Galactica

  John Maier, Ewen Campbell, Dieter Gerlich and Mathias Holz

In 1919 Heger published observations of some curious absorption lines in the spectra of stars. These lines were later shown to be due to material in the interstellar medium in the line of sight and not associated with the background star. The lines were broader than atomic lines (and so possibly molecular) and have since been called the Diffuse Interstellar Bands DIBs. At the present time some 400 are known and they have been well documented observationally and although scores of suggestions have been made as to the possible carriers until now no single DIB has been identified. This is strange as the carrier or carriers must be stable in the interstellar medium and yet no terrestrial species has been found to correlate with any observed band.  A consensus has grown that the carriers are probably molecular species although some favoured absorption by atoms in grains.

At last after nearly 100 years the group of John Maier in Basel has made the first breakthrough by assigning two DIBs unequivocally to C60+ the positive ion of C60. This remarkable achievement was no accident as it was the result of many years of painstaking work developing state of the art spectroscopic techniques to create conditions in the laboratory which simulated the extremely low temperatures and low pressures in the interstellar medium.   The C60 molecule Buckminsterfullerene was serendipitously discovered in our experiments in 1985 which had as their second aim the identification of the DIBs. The fact that this molecule was spontaneously created under conditions in which possible contenders for DIB carriers might also be produced seemed like an intriguing coincidence worth following up. In 1987 I suggested that if C60 was a likely DIB contender in interstellar space than the ambient radiation field would almost certainly ensure that it must be ionised as C60+.  Maier in 1993 measured the spectrum of the ion in a matrix and found two strong lines the frequencies of which were used by Foing and Ehrenfreund to search for new DIBs close of these frequencies. They found two lines in reasonable correspondence however significant matrix shifts meant that for an unequivocal assignment the spectrum had to be measured in the gas phase at low-temperature; a daunting task. Maier has spent much of the intervening time developing superb state-of-the-art experimental techniques to achieve just this and this brilliant breakthrough is a result of his determined approach to solving one of the most important and long-lasting puzzles in science. It is a bit sad of course that this puzzle has now be solved at least in part however there are several hundred lines still to identify but it now seems highly likely that other C60 analogues are also present in the ISM and one might conjecture many of the other lines are due to these analogues which could be endohedral species in which an atom of say sodium or calcium is trapped inside the fullerene cage or the atom is attached to the outside of the cage.  Such species should display quite strong spectra and be detectable in the future although laboratory measurement will still be a daunting task.

It is incredible to think that one of the most abundant set of species in interstellar space may be these carbon cages and yet they are almost non-existent in the terrestrial environment and took until nearly the end of the 20th century to discover.  The molecule was under our noses all the time in flames (indeed it is now made in bulk by combustion of methane) and at the same time its signature was being recorded whenever astronomers observed stellar spectra.

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Links to relevant articles, videos etc











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The Spectrum and the fit to the DIBs


Figure 1 | Gas-phase laboratory spectra of C60+ at 5.8 K. Gaussian fits to the experimental data (circles) are represented by the solid black lines.  The vertical red lines are the rest wavelengths, 9,577.4 +/- 0.2A˚ and 9,632.6 +/- 0.2A˚ of two reported DIBs


3 2 2 | N AT U R E | VO L 5 2 3 | 1 6 J U LY 2 0 1 5

Laboratory confirmation of C60+ as the carrier of two diffuse interstellar bands
E. K. Campbell, M.Holz, D. Gerlich & J. P. Maier

The diffuse interstellar bands are absorption lines seen towards reddened stars. None of the molecules responsible for these bands have been conclusively identified2. Two bands at 9,632 A˚ and 9,577 A˚ were reported in 1994, and were suggested to arise from C60+  molecules, on the basis of the proximity of these wavelengths to the absorption bands of C60+ measured in a neon matrix. Confirmation of this assignment requires the gas-phase spectrum of C60+. Here we report laboratory spectroscopy of C60+  in the gas phase, cooled to 5.8 kelvin. The absorption spectrum has maxima at 9,632.7 +/-  0.1  A˚ and 9,577.5 +/- 0.1  A˚ and the full widths at half-maximum of these bands are 2.2 +/- 0.2  A˚ and 2.5 +/- 0.2 A˚, respectively. We conclude that we have positively identified the diffuse interstellar bands at 9,632 A˚ and 9,577  A˚ as arising from C60+ in the interstellar medium.

C60+ DIB orig manuscript-1

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22-pole Ion Trap

Producing cold molecules becomes more difficult as the size of the species increases. This is due to the fact that larger molecules have more internal vibrations where the energy can be stored. Therefore very big molecules, like polycyclicaromatic hydrocarbons (PAHs) and fullerenes, cannot be cooled efficiently during the short-time scales involved in a supersonic expansion. An alternative approach is to collect the ions in an ion trap and cool them down through collisions with a cold buffer gas, like helium or argon.



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John M HK Don H


Photograph taken by Jon Hare of John Maier, Harry Kroto and Don Huffman on 15 July 2015 at a symposium celebrating the 30th anniversary of the discovery of C 60 at which John first announced the unequivocal identification of one carrier of the diffuse bands. The first time that any of these features had ever been identified.

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Kroto-1994-Nature  1994 News and Views Article

From YouTube

“They’re wrong” …Response to the comment that “…others have said that…C60 is nothing like a match for the carrier of the DIBs.  The last minute of the BBC Horizon/NOVA programme “Molecules with Sunglasses”

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Unless you’re right! … Othello III iii
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 Timeline (Details below)

1919-22  Heger discovers some odd lines in the spectra of various stars

1934-36 Merrill shows they are interstellar lines

1963-   Herbig starts his catalogue of the lines

1969  Becklin et al  discover the cool red giant star IRC+10216

1975-8   Alexander, Kroto and Walton at Sussex University measure the microwave spectrum of HC5N and Kirby Kroto and Walton measure HC7N

1977  Huffman starts working on the problem of interstellar dust

1975-78   Avery, Broten, McLeod, Oka, Kroto, Kirby and Walton using the Sussex frequencies by radio astronomy using the NRC telescope discover the fact that long carbon chain polyynes are unusually abundant in interstellar space.

1977  On the basis of the polyyne discovery Douglas, also at NRC, suggests that carbon chains related to those seen in 1975 might be responsible for the DIBs

1978  Winnewisser and Walmsley discover HC5N and HC7N in IRC+10216 indicating the chains were formed in stars…a crucial observation!

1985  In experiments designed to is simulate the conditions in IRC+10216 by Kroto, Heath, O’Brien, Curl and Smalley discover C60 serendipitously.  The experiments aimed to show that the carbon chains can form readily under conditions similar to those conjectured to occur in the warm atmospheres of red giant carbon stars. C60 was suggested as a DIB contender.

1987-1996  The possibility that C60+ and its analogues are good candidates for carriers of some of the diffuse bands suggested. This suggestion based on recognition that the places where the DIB carriers reside must be bathed in radiation up to 13.6 eV (the ionisation potential of the H atom) which indicated that any carriers were almost certainly ionised and only stable species under these conditions are likely contenders (Kroto)

1988   The above 1987 C60+ conjecture further discussed by Leger and d’Hendecourt

1990   C60 isolated almost simulaneously by the German-American group of Kraetschmer, Lamb, Fostiropoulos and Huffman and the Sussex University group of Taylor, Hare, Abdul-Sada and Kroto making it possible to carry out laboratory studies of the fullerenes

1992-93  The C60+ and analogues (ionised M@C60 and M.C60) conjectures discussed in more detail by Kroto and Jura and Hare and Kroto etc.

1993   Maier’s group in Basel made one of the most important laboratory observations in the whole story by detecting two lines of C60+ trapped in a neon matrix. These lines of course are shifted by matrix effects from the gas phase positions.

1994    Foing and Ehrenfreund carried out a search in the IR based on the detected two new diffuse bands tantalisingly close to the Basel matrix measurements indicating that it is now very important to measure the C60+ lines in the gas phase at low temperatures under conditions similar to those in the interstellar medium. A daunting task which will do need the development of ingenious state-of-the-art laboratory techniques.

2010    Cami et al identify C60 vibrational lines in the Spitzer satellite spectra from the outflows of a star

2015     Brilliant experiment by Maier’s Group unequivocally identifies the carrier of two DIBs as the ion C60+. This is the first time that any of these lines 1st discovered in 1919 has ever been identified. This is a magnificent achievement in solving a mystery that has lasted almost a century. Published Nature 523   1 6 July 2 0 1 5 almost 30 years after the discovery of C60.

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The Diffuse Interstellar Bands (P Jenniskens F -X Desert)

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1919-1922  Heger discovers the DIBs

Nearly 100 years ago Mary Lea Heger discovered diffuse bands in the spectra of stars due to some sort of material maybe molecules in the space between stars and Earth.  A map of the data from the Sloan Digital Sky Survey, by a team from Johns Hopkins produced this map. Red indicates areas with the most abundant DIB molecules, blue the least.

DIB Fit2



The original Mills spectrograph on the 36-inch refractor at Lick Observatory as used by Mary Lea Heger (inset) for her observations of the first DIBs. The image of Heger, from the 1919 Blue & Gold Yearbook, is courtesy of the Bancroft Library, University of California at Berkeley.


1934-36  Merrill shows they are interstellar

In 1934 Merrill showed one band did not share the varying Doppler shifts exhibited by atomic stellar lines associated with the orbital motion of the binary background star and so demonstrated the band was interstellar

1963-1995  Herbig starts his reviews

Herbig, G. H. (1995). “The Diffuse Interstellar Bands”. Annual Review of Astronomy and Astrophysics


1969   Becklin et al discover the Red Giant Star IRC+10216

Becklin, E. E. et al. (December 1969). “The Unusual Infrared Object IRC+10216”. Astrophysical Journal 158: L133



 1974-78   The microwave spectra of long carbon chains measured at Sussex University

Professors Harry Kroto And David Walton

with David Walton who pioneered the synthesis of long carbon chain polyynes

1975-1978 Radioastronomy detection of the long chains in space by the Sussex/NRC team
 Polaroid image of the detection of HC7N with the Algonquin telescope at the moment that the signal appeared on the oscilloscope


Microwave spectra of long carbon chain polyynes

1978   Detection of the long chains in the red giant IRC +10216

Astrophys. 70, L37-L39 (1978) Letter to the Editor

The Detection of HC5N and HC7N inIRC + 10216 G. Winnewisser and C. M. Walmsley 



Guisbert Winnewisser and Takeshi Oka (a while ago!}

Takeshi was not only a part of the radio astronomy team that detected the carbon chains in the interstellar medium but also detected the spectrum of H3+ in the laboratory…a fantastic achievement.

1977   Conjecture that carbon chains might be carriers of the DIBs

Douglas, A. E. Nature 269, 130−132 (1977).


1985   The discovery of C60 – a Rice/Sussex collaboration


Jim Heath and Sean O'Brien

Jim Heath and Sean O’Brien



The discovery of C60

When we discovered the fullerenes in 1985 in laboratory experiments which simulated the chemical conditions in carbon rich red giant stellar atmospheres they stimulated me to think about their possible existence in stellar outflows and in the general interstellar medium.  In fact there were two reasons for carrying out the 1985 experiments: one was to simulate the chemical conditions which were responsible for production of the long carbon chains which we had discovered in the late 70s and which I thought must have been created in the atmospheres of cool carbon red giant stars. The second reason was to follow up on the idea that carbon chains are possible carriers of the diffuse interstellar bands. Our long chain discoveries were carried out at NRC in Canada and this stimulated Alec Douglas to suggest that the carbon chains might be responsible for them. This second experiment was to be a resonant two photon ionisation experiment in which the first photon would be at a DIB frequency and we would hope to see a specific chain detected by mass spectrometry. Needless to say the unexpected appearance of C60 diverted us from this extremely tricky second experiment. Capture c60 image

Fullerene Molecules in Space: C60, ions such as C60+, endohedral fullerenes M@C60, and analogues M…C60 etc almost certainly ionised and their possibility as carriers of the Diffuse Interstellar Bands, DIBs


1987 – 2015    Arguments in favour of C60+ and its analogues as carriers of the diffuse interstellar bands

Then particularly intriguing was the possibility that C60 or some analogues (ionised species such as C60+, endohedral fullerenes M@C60+, and analogues M+…C60) might be carriers of the Diffuse Interstellar Bands.  It seemed that it might not be a coincidence.  The radiation field in the diffuse clouds of interstellar space is such that molecules must be ionised. The possibility that some sort of carbon molecules might be involved in the DIB mystery was one of the reasons for carrying out the original 1985 C60 discovery experiments.

Kroto, H. W. in Polycyclic Aromatic Hydrocarbons in Astrophysics (eds Léger, A., d’Hendecourt, L. & Boccara, N.)  197−206 (Reidel, Dordrecht, 1987).

In this 1987 paper (below) there are predictions made on the possible existence of C60 and its analogues in stars and interstellar space in particular as the positive ion C60+ as well as complexes M…C60+ and M@C60+ with other species M such as atoms (H, He, Na, K, Ti, Ca, N, O etc) and also as possible carriers of the Diffuse Interstellar Bands, DIBs.

 Extracts below.

HWKroto-1987 discussing the possibility of C60 and its analogues in space and as DIB carriers

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Ann. Phys. Fr., Vol. 14, N°2 1989, pp. 169-180
DOI: 10.1051/anphys:01989001402016900

The role of linear and spheroïdal carbon molecules in interstellar grain formation

H.W. Kroto

School of Chemistry and Molecular Sciences, University of Sussex, Brighton, BN1 2QJ, G.B.

The recent discovery that a uniquely stable, spheroidal, carbon molecule consisting of 60 atoms, C 60 Buckminsterfullerene, forms spontaneously when carbon vapour nucleates has opened up a new and exciting perspective on the chemical and physical properties of carbon. The observations, shed new light on the detailed mechanism of the carbon clustering process itself and appear to have particularly important implications as far as carbon particle formation is concerned in such varied scenarios as combustion chemistry and circumstellar dust formation. The new perspective appears to offer the possibility of an understanding of many hitherto unexplained aspects of the behaviour of solid and fluid forms of condensed carbon. The discoveries were made during laboratory experiments aimed at an understanding of the relationships between carbon chain molecules and macroscopic carbon grains in circumstellar shells and interstellar space. The results suggest that in addition to the chains and grains, the C60 molecule, probably in the form of the ion C60+ in the less shielded regions, is ubiquitously present and perhaps responsible for some of the interstellar spectroscopic features such as the some of the Diffuse Interstellar Bands. Further study of small carbon particles which form in the gas phase has resulted in the discovery that they have quasi-icosahedral spiral shell structures. It seems highly likely that related species which include hydrogen are responsible for some of the Unidentified Infrared Bands. The rôle that C60, C60 + and icospiral carbonaceous particles play in the interstellar medium should soon be accessible to verification by a combination of laboratory experiment and astronomical spectroscopy.

Science. 1988 Nov 25;242(4882):1139-45.
Space, stars, c60, and soot.

Kroto Space, Stars, C60, and Soot (1988)_


Although carbon has been subjected to far more study than all other elements put together, the buckminsterfullerene hollow-cage structure, recently proposed to account for the exceptional stability of the C(60) cluster, has shed a totally new and revealing light on several important aspects of carbon’s chemical and physical properties that were quite unsuspected and others that were not previously well understood. Most significant is the discovery that C(60) appears to form spontaneously, and this has particularly important implications for particle formation in combustion and in space as well as for the chemistry of polyaromatic compounds. The intriguing revelation that 12 pentagonal “defects” convert a planar hexagonal array of any size into a quasi-icosahedral cage explains why some intrinsically planar materials form quasi-crystalline particles, as appears to occur in the case of soot. Although the novel structural proposal has still to be unequivocally confirmed, this article pays particular attention to the way in which it provides convincing explanations of puzzling observations in several fields, so lending credence to the structure proposed for C(60).


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a postbuckminsterfullerene view of carbon in the galaxy_hare and kroto_(1992 Acc Chem Res)

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Paper discussing C60 and its various analogues in space and as carriers of the DIBs
Title: Circumstellar and interstellar fullerenes and their analogues

Authors: Kroto, H. W. & Jura, M.
Journal: Astronomy and Astrophysics (ISSN 0004-6361), vol. 263, no. 1-2, p. 275-280

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Discussion with Mike Jura at a conference on interstellar dust at Clemson in 1990

Paper on Dust an Interstellar chain formation  nph-iarticle_query

photograph by Don Clayton. See other historical images here on Don’s website



C60, Buckminsterfullerene and/or its complexed exo­ hedral and endohedral analogues, most likely in ionized form, may be ubiquitously distributed in space and stars. The com­ plexes involving abundant elements (Na, K, H, 0, etc.) should exhibit strong charge transfer bands with characteristics similar to those of certain unidentified astrophysical spectroscopic features.

Key words: fullerenes – C60M + – exohedral ion complexes – diffuse bands – charge transfer spectra


circumstellar and interstellar fullerenes and their analogues_(1992 KROTO A&A.)

Kroto, H. W. in Polycyclic Aromatic Hydrocarbons in Astrophysics (eds Léger, A., d’Hendecourt, L. & Boccara, N.) 197−206 (Reidel, Dordrecht, 1987).

Further discussion of the above conclusions re C60 and C60+ and the DIBs


Kroto, H. W. & Jura, M. Astr. Astrophys. 263, 275−280 (1992).


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From YouTube

“They’re wrong” …Response to the comment that “…others have said that…C60 is nothing like a match for the carrier of the DIBs.  The last minute of the BBC Horizon/NOVA programme “Molecules with Sunglasses”


At this point I like the catchphrase from Dennis Potter’s brilliant  TV film: “The Singing Detective”

Singing Detective

am I right or…


Full (NOVA US) version here in 4 parts entitled “The Race to Catch the Buckyball” a nonsense title as there was no race really.  Unfortunately (maybe the BBC? …see below) has closed down the much better original UK version, beautifully narrated by Juliet Stevenson, entitled “Molecules with Sunglasses” … a much better scientifically and historically accurate title, especially in retrospect as a molecule seems to be the most resilient one with respect to the radiation fields in interstellar space!



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1990 Extraction of C60 so making laboratory measurements possible

Extraction of C60





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1993 The key laboratory measurement by the Basel group of the matrix spectrum of C60+

In 1993 John Maier’s Basel group published some fascinating results on C+60 trapped in a neon matrix. They detected two strong bands at long wavelength.

Chemical Physics Letters Volume 211, 1993, Pages 227–234

Electronic and infrared spectra of C+60 and C60 in neon and argon matrices

Jan FularaMichael JakobiJohn P. Maier


The electronic transitions of C+60 and C60 isolated in 5 K neon matrices were detected with well-resolved vibrational structure after NeI irradiation of C60 during deposition. On the basis of a C+60 spectrum obtained by growing a matrix with a mass-selected C+60 ion beam, overlapping peaks in the electronic spectra were assigned to either C+60 or C60. The vibrational frequencies 1406 and 1332 cm−1 for C+60, and 1386 and 1202 cm−1 for C60, were identified in a neon matrix from the infrared spectrum. C60 was also detected after codepositing Na and K with C60, without irradiation. Relevance of the data to interstellar observations is discussed.


C60+ matrix-1993


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1994  A search based on the Basel matrix spectra detected two new DIBs close to the laboratory frequencies 

Foing and Ehrenfreund followed up the measurements of the two lines by the Basel group and searched in the Infra Red, a region which has only recently been developed and found two bands in very good ageement taking into account matrix shifts.

(B H  Foing and P Ehrenfreund Nature 369, 296 – 298 (26 May 1994))



More than a hundred well-defined absorption bands, arising from diffuse gas in the interstellar medium, have been observed in the visible and near-infrared spectra of stars 1–4. The identity of the species responsible for these bands has remained unclear, although many possibilities have been suggested5,6. Carbon-based molecules ubiquitous in the interstellar medium have been widely favoured as potential carriers of some of the diffuse interstellar bands7–10,29; in particular, C60 + has been thought to be a promising candidate9,29. Here we present the results of a search for C60 + in the near-infrared spectra of seven stars, based on recent laboratory measurements of the absorption spectrum of this species11–13. We find two diffuse bands that are coincident (within 0.1%) with laboratory measurements on C60 + in a Ne matrix11. From this observation and the total absorption, we estimate that 0.3–0.9% of interstellar carbon is in the form of C60 +. The molecule is very stable, which should allow it to survive in the interstellar medium for a long time14, but the inhibition of C60 + formation by hydrogen probably limits its abundance.

11)   Fulara, J., Jakobi, M. & Maier, J. P. Chem. Phys. Lett. 211, 227−234 (1993).

12)   Kato, T. et al. Chem. Phys. Lett. 180, 446−450 (1991). |

13)   Gasyna, Z., Andrews, L. & Schatz, P. N. J. phys. Chem. 96, 1525−1527 (1992).

14)    Kroto, H. W. Nature 329, 529−531 (1987).

15)    Kratschmer, W., Lamb, L. D., Fostiropoulos, K. & Huffman, D. R. Nature 347, 354−358 (1990).




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Unequivocal verification of this possible assignment of C+60 as a DIB carrier will require the accurate laboratory measurement of these bands in the gas phase at very low temperature, a somewhat daunting task.


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2010    C60 detected in a Space 

The possibility that C60 analogues from and we come back I the here are  carriers of some DIBs has become even more plausible due to the extremely exciting detection of this species and C70 in the outflows of certain stars by Cami and coworkers.

Detection of C60 and C70 in a young planetary nebula.    Science. 2010 Sep 3;329(5996):1180-2.

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Red C60 and Blue C70

Cami J1, Bernard-Salas J, Peeters E, Malek SE.



Steward/NOAO Joint Colloquium Series – Download free …


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“After Nearly 100 Years the Hunt May Be Up for the Carriers of the Diffuse Interstellar Bands

Harry Kroto

The age-old awe that man has had for the heavens has driven almost all aspects of human culture and knowledge and resulted in many useful technologies. As spectroscopic techniques developed and were allied with telescopes many fascinating discoveries were made. One early surprise was that Space – between stars – was not empty; indeed interstellar space was found to contain numerous atoms, molecules and dust particles. The development of radio telescopes has revolutionized our understanding of the molecular constitution of the interstellar medium ISM. A recent surprise that the element carbon had up its sleeve was the existence of C60, Buckminsterfullerene, the third well-defined form of carbon. The possibility that C60 and derivatives exist in space was suggested by the fact that the original discovery was made serendipitously during our laboratory experiments in 1985 designed to simulate the atmospheric conditions in cool red giant carbon stars.. This conjecture was beautifully confirmed by NASA’s Spitzer satellite telescope and this suggests that C60 or some analogues may be responsible for some of the Diffuse Interstellar Bands, DIBs.

The first set of these DIBs was first observed in 1919 and many more have since been observed and have puzzled scientists ever since. In 1993 John Maier’s group in Basel detected two lines of C60+ in matrix studies and these observations were followed up by Foing and Ehrenfreund who observed two new diffuse interstellar bands very close to Maier’s observations which are of course subject to solid-state matrix shifts. Although the astrophysical lines were very close, indeed tantalisingly so, unequivocal confirmation requires laboratory measurement of C60+ lines in the gas phase at very low temperature… an extremely demanding task indeed. The very close proximity of the laboratory and astrophysical measurements however make the measurement well worth attempting.

The fact that this species seems to have been hiding in the dark recesses of the Galaxy since time immemorial brings to mind the mysterious character, Harry Lime, lurking underground and in the dark streets of Vienna, made famous by Orson Welles in the classic movie The Third Man. In fact we now know that the molecule forms fleetingly within sooting flames but seems to be immediately destroyed by fast aggregation reactions and/or as it passes through the flame barrier into an oxygen containing atmosphere. This is yet another example of the remarkably synergistic relationship between terrestrial and space science. In these difficult times it lends useful support for the fundamental value of “Blue Skies” or perhaps more accurately Black Skies cross-disciplinary research.

Capture c60 image

Claudine and Reg Colin’s dog Mimi explaining to John Maier how he should tackle the problem of detecting C60+ in the gas phase at low temperature.


A well earned cigar after 20 years of effort




22-pole Ion Trap

Producing cold molecules becomes more difficult as the size of the species increases. This is due to the fact that larger molecules have more internal vibrations where the energy can be stored. Therefore very big molecules, like polycyclicaromatic hydrocarbons (PAHs) and fullerenes, cannot be cooled efficiently during the short-time scales involved in a supersonic expansion. An alternative approach is to collect the ions in an ion trap and cool them down through collisions with a cold buffer gas, like helium or argon.



Recent publications:

Capture c60 image



Capture c60 image