Radiative lifetime measurements of the CO and CD stretching modes in DCO+

The radiative decays of vibrationally excited DCO+ ions produced by dissoci ative ionization of CD3CDO have been investigated using the monitor ion tec hnique in a Fourier transform ion cyclotron resonance spectrometer. The rad iative lifetimes of the nu(1) (nu = 1, 2) and nu(3) (nu = 1) stretching mod es have been determined. For the CO stretching nu(3) the experimental lifet ime (24 +/- 2.5 ms) is in good agreement with the theoretical values calcul ated for DCO+ and HCO+. For the CD stretching nu(1) the experimental lifeti mes (112 +/- 22 ms) for nu = 2 and (226 +/- 45 ms) for nu = 1 are about fou r times larger than the theoretical values, The disagreement between experi ment and theory is possibly due to a strong coupling of nu(1) with a long l ived state which has not been taken into account in the calculations. For t he bending mode nu(2), only a lower limit of the very long lifetime could b e evaluated. (Int J Mass Spectrom 185/186/187 (1999) 131-137) (C) 1999 Else vier Science B.V.