Abstract

We use tunable excitation from a Cr:LiSAF laser at 225 nm and 270-300 nm to excite emission from B. subtilis (globigii) spores (BG) and E. coli vegetative cells suspended in water. We report the dispersed fluorescence between 250 and 660 nm for both species. The 3400 cm⁻¹ Raman shift from water provides intrinsic calibration which allows the determination of absolute fluorescence yields. Photobleaching of BG spores at 225, 275 and 300 nm shows an increase at shorter wavelengths. Reproducible spectra can only be obtained at laser powers below 5 mJ cm⁻²pulse⁻¹.

© 1996 Optical Society of America