Deuterium isotope effect on single vibronic level photochemistry of formaldehyde ∼A, 1A2): Fluorescence quantum yields, radiative and non-radiative transitions

✍ Scribed by Richard G. Miller; Edward K.C. Lee

• Publisher: Elsevier Science
• Year: 1976
• Tongue: English
• Weight: 361 KB
• Volume: 41
• Category: Article
• ISSN: 0009-2614
• DOI: 10.1016/0009-2614(76)85245-1

✦ Synopsis

Ruorescence quantum yields for various single vibronic levels and fluorescence decay times for the 4l level have been measured for HzCO, HDCO, and D#3. implications of the observed rates of radiative and non-radiative transitions to vibronic cciupfing mechanisms and p~otoc~emisr~ are discussed.

Recently we have reported the radiative lifetimes @R) and eon-radiative lifetimes (rNR) of seIected vibronic levels of the first excited singlet state of H,CO (Ssr ,l AZ) [if. Because of our interest in understanding the primary photochemical processes in formaldehyde as well as in providing basic experimental information pertinent to the photochemical laser isotope separation of deuterium [2,3], we have studied the fluorescence excitation spectroscopy of the x 'A, -x IA, transitions of HJXO and DzCO by which the fluorescence quantum yields @BF) can be obtained. Additional measurements of the fluorescence decay times (yF) then permit the calculation of the values of rR and 7NR from the relationships 7R = rF/aF and TNR = TF/(I -TF), respectively. All of the experiments were run at room temperature, 23"C, and the same experimental procedures as employed earlier in our faboratory for measuring 6$ 141 and fF f5] were US&. ?Ye have measured the v&es of QtF and TV for a number of single vibronic levels (SVLj of HDCO(S, ) and D$X(SI), but due to the space lactation we shall mainly coti'ne our discussion to the 4' level, the * This research has been supported by t&e office of Nava3 Research Contract N-00014-7X48 13.