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Evaluation of the effective work functions of a binary salt using thermochemical data on its two constituent elements

1983; Elsevier BV; Volume: 52; Issue: 2-3 Linguagem: Inglês

10.1016/0020-7381(83)85045-1

1873-3034

Hiroyuki Kawano, Tsutomu Kenpō, Hiroshi Koga, Yoshiaki Hidaka,

Thermal and Kinetic Analysis

The effective work functions (Φ+ and Φ−) for the emission of positive and negative ions (M+ and X−), respectively, from an inhomogeneous surface of a binary salt (MX) such as an alkali-metal halide are investigated on the basis of experimental results achieved in our previous work. Each of the work functions is generally expressed as a function of the thermochemical values of the constitutive elements. Φ+ = I + D + D0 − 2D+ Φ− = A − D − D0 + 2D− where I is the first ionization energy of the electropositive atom M, A the electron affinity of the electronegative atom X, D the dissociation energy of the molecule MX, D0 the desorption energy (or the heat of sublimation) of MX, and D±the desorption energy of M+ or X−.