Radiative lifetimes for the A 1Pi and B 1Delta states of the CH/+/ molecule with application to the CH/+/ abundance in zeta Ophiuchi

Abstract

Using an electron-beam phase-shift apparatus, we have measured radiative lifetimes of 270 + 75 ns and 290 I 75 ns, respectively, for the V' = 1 and 2 levels of the A `11 state of the CH + molecule, and lifetimes of 180 I 50ns and 165 I 50 ns for the V' = 0 and 1 levels, respectively, of the B `A state of CH+. We find relatively poor agreement with lifetimes calculated from the theoretical transition moment of Yoshimine et al. where lifetimes of 840 and 885 ns are predicted for the V' = 1 and 2 levels of the A `11 state. Closer, but still unsatisfactory, agreement is found with the lifetimes of 495 I 50 ns and 530 I 50 ns found experimentally for V' = 1 and 2 of the A `11 state by Brzozowski et al. Although this range of values is still undesirably large, and the origin of the discrepancies obscure, of 0.014 I 0.003 is recommended from the data. This f-value represents a considerable improvement in the reliability of the oscillator strength, and concomitantly in column densities from observations and the radiative recombination rates calculated from theory. Subject headings: molecules - molecules, interstellar - spectra, laboratory - stars, individual - transition probabilities