Time-resolved fluorescence spectra of DaCO were measured as a function of sample prcssutc. The result tttdtutcs the occurrence of rolat~onal and vtbrational relaution between ewrted states. The magnetic lield effect on fluoresccncc from DzCO excited by a N2 laser depends on the nature of the vlbroruc levels I. introduction Photophysical and photochemrcal properties of vibronic levels of the x IA2 state of formaldehyde have been studied extensively in the gas phase [l-lo]. The magnetic field effect on the fluorescence of D2CO excited to the 4O level has been studied previously by using pulsed lasers [9] and a mercury lamp [ 10) as excitation sources. The effect is collision-induced and oscillates against the magnetic field with minima at 5 and 10 kG [9]. The fluorescence spectrum of D2C0 excited to vibromc levels higher than the 4' level of the t A, state has not yet been measured because of the very weak intensity and the occurrence of photodecomposition.
In the present work, a N2 laser has been used to excite D2C0 to vibronic levels higher than the 4l level of the lA2 state and the time-resolved fluorescence spectra have been measured for the first tune. From the pressure dependence of the spectra we have obtained information about collisional, rotational, and vibrational relaxations. A difference in the magnetic field effect between the vrbronic levels has been observed and drscussed.