Laser-induced fluorescence in gaseous I2 excited with a green laser pointer

A green laser pointer can be used in a "flashy" demonstration of laser-induced fluorescence in the gas phase, by directing the beam of the laser through a cell containing I2 at its room temperature vapor pressure. The demonstration is a good one to provoke discussion, and the explanation of the on-off behavior provides valuable insight into the requirements for LIF and the properties of lasers. On the other hand, if this source is to be used to record fluorescence spectra for quantitative analysis, it will be necessary to use an array-type detector and to be aware that the time-integrated spectrum may contain contributions from numerous (v′, J′) levels. Under the assumption t hat it is changing cavity temperature that is responsible for the varying wavelength of the laser, it is conceivable that one can modify such a pointer to permit control of its temperature and hence its wavelength. I am looking into this possibility.