Excitation Transfer in Helium Afterglow

electronic state because of the relatively large number of other states of He2 lying within kT of the 3p 3IIg • n is interesting to note that the collection of statistically significant data is limited at both high and low pumping intensities. In the former case, the use of an excessively intense correlated source appears to cause progressively shorter lifetimes of the enhanced population as the intensity is increased beyond some threshold value. Conversely, the use of a source of insufficient intensity does not produce statistically significant fluorescent signals in a reasonable number of laser pulses. The relatively short operational lifetime of the flashlamp pumped dye laser systems places a limit of about 1000 pulses on the duration of an experimental measurement. It appears that as nitrogen pumped dye laser systems6 are beginning to achieve radiancies comparable to those quoted here for the flashlamp system, those devices may eventually offer considerable improvement to such fast reaction studies since their mean time to instability is substantially greater.