Evaporation mechanism of solids

Somorjai, Gábor A.; Lester, Joseph E.

doi:10.1016/0079-6786(67)90004-0

Cited by 63 publications

(19 citation statements)

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“…The vaporization rate of many solids into vacuum have already been found to be much smaller than the maximum vaporization rate which can be calculated, from equ'ilibriumvapor pressure data (Somorjai and Lester, '1967). For many solids (As , [Brewer andKane, 1955J, P [Kane 1955J, GaAs) the presence of liquid metals on the vaporizing surface may increase the sublimation rate by orders of magnitude to that of the maximum rate.…”

Section: Low Energy Electron Diffraction (Leed) Study Of the Vapmentioning

confidence: 99%

“…Since all atoms in such a crystal faee have equal probability to vaporize the overall evaporation rate is given by (Somorjai and Lester, 1967)…”

Section: Principles Of Vaporization Studiesmentioning

confidence: 99%

“…It is customary (Somorjai and Lester, 1967) to express the deviation of the vacuum evaporation rate, J V , from the m~imum, equilibrium rate, JV in terms of the evaporation coefficient, ex, which is given by, max (6) If the vacuum evaporation rate is equal to the maximum rate,CX(T) = 1,…”

Section: Principles Of Vaporization Studiesmentioning

confidence: 99%

“…Its magnitude reflects' the overall energy necessary for the surface atoms to participate in the rate limiting reaction step (or steps) (Somorjai and Lester, 1967)~o Vaporization is a multi-step process in which atoms break away from their lattice sites, 'may diffuse on the surface until they are ready to vaporize. For many solids the surface atoms must undergo teari:angements such as association, dissociation or charge transfer prior to desorption from the vaporizing surface (Somorjai and Lester,1967)…”

Section: Principles Of Vaporization Studiesmentioning

confidence: 99%

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Studies of the Sublimation Mechanism of Solids

Somorjai

1969

Advances in High Temperature Chemistry

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Section: Low Energy Electron Diffraction (Leed) Study Of the Vapmentioning

confidence: 99%

“…Since all atoms in such a crystal faee have equal probability to vaporize the overall evaporation rate is given by (Somorjai and Lester, 1967)…”

Section: Principles Of Vaporization Studiesmentioning

confidence: 99%

Section: Principles Of Vaporization Studiesmentioning

confidence: 99%

Section: Principles Of Vaporization Studiesmentioning

confidence: 99%

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Studies of the Sublimation Mechanism of Solids

Somorjai

1969

Advances in High Temperature Chemistry

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“…The effect of impurities on the vaporization behavior of binary semiconductors has been well documented. 5 …”

Section: Introductionmentioning

confidence: 99%

Studies of the Evaporation Mechanism of Sodium Chloride Single Crystals

Lester

Somorjai

1968

The Journal of Chemical Physics

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The vacuum evaporation rate of the (100) face of pure sodium chloride single crystals has been measured with a vacuum microbalance in the temperature range 450°–650°C. The steady-state vaporization rates of pure crystals with dislocation densities of ∼1 × 106/cm2 were lower by about a factor of two than the maximum thermodynamic rate (ᾱυ ≈ 0.5). When the dislocation density was increased an order of magnitude (to ∼ 107/cm2) by straining the crystals, the steady-state evaporation rate increased to approximately the thermodynamic rate (ᾱυ ≈ 1.0). The relative vaporization rates of monomer and dimer were measured using a quadrupole mass spectrometer. Vaporization activation energies ED* = 53 ± 1 kcal/mole and ED* = 62 ± 1 kcal/mole were found for the monomer and dimer, respectively, in the temperature range of the experiments for low dislocation crystals. No dependence of the monomer to dimer ratio on the dislocation density was detected. The presence of the divalent cation impurity, Ca2+, in the NaCl crystals markedly reduced the vaporization rate and increased the activation energy of vaporization. Crystals doped with 300 ppm Ca2+ exhibited vaporization rates approximately an order of magnitude lower than the maximum thermodynamic rate (ᾱυ ≈ 0.1). The average activation energy of vaporization for these crystals was Ē* ≈ 63 kcal/mole as computed from the total rate of vaporization. The monovalent impurities, Br−, OH−, O2−, had no detectable effect on the vaporization rate. An evaporation mechanism was postulated which could account for the experimental observation.

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Thermal Decomposition of Solids and Melts

Львов

2007

Hot Topics in Thermal Analysis and Calorimetry

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Evaporation mechanism of solids

Cited by 63 publications

References 59 publications

Studies of the Sublimation Mechanism of Solids

Studies of the Sublimation Mechanism of Solids

Studies of the Evaporation Mechanism of Sodium Chloride Single Crystals

Thermal Decomposition of Solids and Melts

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