DEPENDENCE OF THE LASER 2-PHOTON IONIZATION SIGNAL OF ANTHRACENE ON THE ELECTRON-MOBILITY AND THE EXCESS ENERGY IN NONPOLAR-SOLVENTS

The photocurrent and photoionization charge of anthracene in various non-polar solvents have been measured under the third-harmonics of a Nd-YAG laser excitation. They are quadratically proportional to the laser pulse energy, though those of water are cubically proportional to them. Anthracene exhibited a larger signal in those solvents in which both the electron mobility and the excess energy are large. Such solvents offered a higher sensitivity for the photoionization technique. Degassing showed only a minor effect. The detection limits were 14 ng/dm(3) (ppt) in hexane and 3.0 ng/dm(3) (ppt) in 2,2,4-trimethylpentane.