Time-resolved detection of singlet oxygen in a transmission microscope

The time-resolved absorption spectrum of singlet oxygen [O-2(a(1)Delta (g)) --> O-2(b(1)Sigma (+)(g))] has been recorded in the region similar to 5100 -5300 cm(-1) from air-saturated polystyrene samples using a microscope atta ched to a step-scan Fourier transform IR spectrometer. Singlet oxygen signa ls were observed with a time resolution of similar to 160 ns from sample vo lumes of similar to 20 nL using moderate data-acquisition times. These data indicate that it is reasonable and worthwhile to consider the further deve lopment of a transmission microscope as a viable tool to create singlet oxy gen images of inhomogeneous samples including samples of biological importa nce.