Mean translational energy

Heating regime Surface temp, (mean) Translational energy Rotational energy Vibrational energy Residence time(ps)... 

Figure 3.18. Variation of the mean translational energy Ef of NO in scattering from Ag(lll) at the initial energies Et and incident angles 0f as noted on the figure. From Ref. [49].

At constant temperature, the observed widths of the spectral functions decrease with increasing mass of the collisional pair. This fact is a simple consequence of the mean translational energy of a pair, jm v = kT, which is the same for all pairs. The interaction time is roughly proportional to the reciprocal root mean square speed, and thus to the square root of the reduced mass. 

Table 2 / Dependence of the mean translational energy ((Et)) and the tilt angle just before desorption (4) ) for NO (v = 0, 2 = 1/2) ofhcp hollow species from Pt(l 1 1) at X = 193 nm.

From consideration of the mean translational energy release in a considerable number of ionic decompositions, the empirical relationship = /0.44n has been found [310]. [E is considered to be equivalent to (E — E0) (see Sect. 8.3.1).] The predictions of eqn. (39) are, therefore, only marginally greater than the experimental energy releases. The use of eqn. (39) has been advocated as a first approximation to the partition of excess energy, E — E0, in the case of a decomposition with a reverse critical energy ER [167, 603]. The partition of ER would be treated separately (see Sect. 8.1.3). 

The mean translational energy releases in the loss of C2H2 from the molecular ion of thiophene exceed the values predicted by phase space theory by about a factor of 2 [152]. The suggestion [152] that the disagreement stems from vibrational energy not being randomised prior to dissociation seems unjustified. The loose model assumed for the transition state would seem to be the prime suspect. 

The translational energy release in the formation of (C02H)+ from acetic acid as determined by this method was negligible [367], suggesting that there was no kinetic shift in this measurement. Most of the measurements upon which eqn. (42) is based have concerned molecules of fewer than 10 atoms and the mean translational energy releases at the measured appearance energies have typically been in the range... 

Figure 14. Mean translational energy, for scattered NO from Ag(l 11) as a function of finai rotational energy for various incident kinetic energies and angies, from Rettner (1988) with permission.

The mean translational energy releases for the formation of both (C3H3) and (C4H4)t following PI of benzene, 1, 5-hexadiyne and 2,... 

Mean translational energy of product ion reported in reference for different energies (EE) of the incident electrons (see Sect. 

The mean translational energy of the product ion at the measured appearance energy (see Sects. 3.1.4 and 8.3) is given in the table. EE Energy of incident electrons (see Sect. 8.3). 

D17.4 The temperature is always high enough for the mean translational energy to be kT, the equipartition value (provided the gas is above its condensation temperature). Therefore, the molar constant-volume heat capacity for translation is Cj nl = R. 

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