ENERGY DISTRIBUTION OF PHOTOELECTRONS EMITTED BY LIQUIDS IN THE VACUUM ULTRAVIOLET.

摘要

A new spectrometer for liquid-phase photoelectron spectroscopy is described. Photons in the 7.5 to 11 eV range were used to induce photoelectron emission from a thin layer of liquid or solution on the rim of a hexagonal rotating (72 rpm) disk target. The kinetic energy distribution curves (EDC's) of electrons emitted into the low pressure vapor of the liquid were measured by analog differentation of retarding potential curves with respect to retarding potential. Second derivative curves (SDC's) were obtained by numerical differentiation of EDC's with respect to the retarding potential. SDC's were compared with the corresponding gas-phase photoelectron spectra. Good correlation was obtained.;The energy level at the bottom of the conduction band in liquids was measured with a new technique involving EDC's.;The Brodsky-Tsarevsky theory of photoelectron emission by solutions was tested by fitting the theoretical EDC equation to experimental EDC's of tetraglyme and lithium thiocyanate with the least square technique. The theory accounts for experimental EDC's quite well provided a Gaussian distribution is introduced for the kinetic energy of the delocalized electrons upon their generation by photoionization in the bulk of the liquid.;The following pure liquids were studied: 1-Cl-6-hydroxyhexane, 2-ethyl-1-hexanol, ethylene cyanohydrin, tetraglyme (tetraethylene glycol dimethyl ether), tetraethylene glycol, triethylene glycol, 1,5-pentanediol and 4-ethylnitrobenzene. Lithium iodide, lithium thiocyanate and hydroquinone were studied in solution in tetraglyme.