James K G Watson
Jim calculating the Eulerian Angle needed to decant the liquid in this tumbler
Jim identified CH as the carrier of an unusually narrow DIB … much narrower than the standard DIBs Binder1
MILJENKO PERIĆ*# in this paper* writes
Among the papers I have been forced to understand, there is hardly one I found so difficult as Watson’s milestone study1 in which he simplified the vibration–rotation Hamiltonian for polyatomic molecules, originally derived by Wilson and Howard.2,3 Just to reproduce five pages of this paper, I needed a whole month, and in order to decipher the extremely complicated formulae in condensed Levi-Civita form, I penned several hundreds of leaves. It seems that other people also had similar problems. I found once in a very serious paper the sentence: “If the Watson’s Hamiltonian is correct …”. Even Watson himself wrote in his paper, “The simplicity of the final result suggests that it should be obtainable by a less complicated calculation than that described here, I have, however, been unable to find a more direct derivation.” As another illustration of the complexity of this study can serve the fact that as Watson needed two years to apply the same procedure for deriving the Hamiltonian for linear polyatomic molecules,4 some researchers questioned his results,5 and that Watson’s answer to this criticism came only seven years later.6 Thus, the goal of the present study was to attempt to derive Watson’s Hamiltonian in a less elegant but simpler, or at least more straightforward, way.
Maybe if Miljenko should have had a shot of single malt whisky to see the JKGW Levi Civita way
Arguably the first DIB identified
MH08 15 min 3:42 FAR-ULTRAVIOLET LINES OF INTERSTELLAR CH, INCLUDING ONE DIB JAMES K. G. WATSON,
Steacie Institute for Molecular Sciences, National Research Council of Canada, Ottawa, Ontario, Canada K1A 0R6.
A far-ultraviolet flash-photolysis spectrum of CH was published in 1969 by Herzberg and Johnsa, but no rotational assignments were made. From their list of 45 lines in the 3d X2 band, there are three near-coincidences with unidentified (UID) interstellar linesb at 1368.74, 1369.13, and 1370.87 A towards the star ˚ Ophiuchi. The spectra of other electronic transitions of CH towards this star are well known, and it was decided to use the interstellar lines as giving the positions of lines with J 00 = 0:5, as is found for the other interstellar bands. From this, a rotational analysis of the complete band was possible, using a Rydberg-state program previously used for the ArH and ArD moleculesc . An interesting aspect of this assignment is that the 1369.13 A line is classified ˚ d as the only established ultraviolet ‘diffuse interstellar line’ (DIB). Different broadening of different lines is also seen in the laboratory spectrum, and is attributed to predissociation, which is found to be greater for lines with upper levels of d parity, including the DIB, than for lines with upper levels of c parity, consistent with the dominant predissociating state being a 2 state. From the n3 -dependence of the splittings of the nd complexes, the rotational structure of the 4d X2 band is predicted, and allows the assignment of the UID interstellar line at 1270.96 A˚ e to the strongest J 00 = 0:5 line of this band.
aG. Herzberg and J. W. C. Johns, Ap. J. 158, 399 (1969). bJ. A. Cardelli, B. D. Savage, and D. C. Ebbets, Ap. J. 383, L23 (1991). cI. Dabrowski, D. W. Tokaryk, M. Vervloet, and J. K. G. Watson, J. Chem. Phys. 104, 8245 (1996). dT. M. Tripp, J. A. Cardelli, B. D. Savage, Ap. J. 107, 645 (1994). eS. R. Federman, J. A. Cardelli, E. F. van Dishoeck, D. L. Lambert, and J. H. Black, Ap. J. 445, 325 (1995).