On the El-E2 Labeling of Energy Levels and the Anomalous Excitation of Interstellar Methanol

Abstract

view Abstract Citations (104) References (17) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS On the El-E2 Labeling of Energy Levels and the Anomalous Excitation of Interstellar Methanol Lees, R. M. Abstract The notation for torsion-rotation energy levels of methanol is reviewed, and it is emphasized that the levels previously labeled as E1 and E2 do not form separate noninterconverting stacks when both positive and negative values of the rotational quantum number k are taken into account. Dropping of the E1-E2 notation in favor of the use of a signed quantum number k is therefore recommended. Experiments are described demonstrating explicitly the transfer of molecules from E1 to E2 levels by one or more allowed electric-dipole transitions. The implications of E1-E2 conversion for anomalous excitation of interstellar methanol are discussed, and it is pointed out that if Ak = 0 collision-induced transitions are preferred strongly in CH8OH-H2 collisions, as was proposed from microwave double-resonance studies, then it is likely that the 5-i 4o and 4-i 3o E transitions detected in Sgr B2 are inverted. Subject headings: excitation and ionization - masers - molecules, interstellar Publication: The Astrophysical Journal Pub Date: September 1973 DOI: 10.1086/152368 Bibcode: 1973ApJ...184..763L full text sources ADS |