EXTERNAL HEAVY-ATOM EFFECT ON DETECTION LIMITS AND LIFETIMES OF PHOSPHORESCENCE IN TIME RESOLVED LASER-EXCITED PHOSPHORIMETRY

A pulsed laser (N2 laser or flash lamp pumped dye laser) time resolved phosphorimeter for phosphorescence lifetime and detection limit measurements is described. The sources of noise in the system are evaluated. Detection limits and lifetimes with the 2 pulsed laser systems are given for several polyaromatic hydrocarbons and drugs at 77 K in 10/90 v/v ethanol/water with no heavy atom, with 0.75 M KI, and with 0.1 M AgNO3. Detection limits with present are generally inferior to those without heavy atom present because of the background flicker noise associated with impurities in the KI. Detection limits with Ag+ present are generally comparable to or better than without Ag+. Detection limits for several molecular species excited with the two laser systems are compared for the three solvent mixtures. © 1979, American Chemical Society. All rights reserved.