Laser mass spectra have been obtained for liquids under ambient conditions; the spectra are identical with those for the same compounds with the use of cold probe (~100 K). Liquids studied include benzene, toluene, benzyl alcohol, benzaldehyde, and acetic acid. Under the conditions employed, water, ethanol, methanol, and glycerol do not yield mass spectra. Laser mass spectra are compared with the electron-impact and chemical ionization spectra of the same compounds. Relative ion yields for benzene were studied as a function of laser irradiance. Two ion-formation regimes can be identified: low-power density and high-power density. Cluster ions were observed for many compounds, and the effect of postacceleration voltage on relative cluster-ion intensity is indicated.
John J. Morelli and David M. Hercules, "Laser Mass Spectra of Liquids Taken at Ambient Pressure," Appl. Spectrosc. 43, 1073-1081 (1989)