The experimental quasielastic scattering spectra (Ref. 4) of , , HD, and a 50:50 mixture of and (circles and error bars) compared to predictions of the present theory (solid line). The computed cross sections are absolute. The intensity scales for the experimental data were established by using the sum rule to normalize the experimentally determined relative intensities.
Decomposition of the calculated quasielastic scattering signal for at 300 K into separate contributions of (i) pure translational (negligible), (ii) without vibrational excitation, and (iii) with vibrational excitation. The theoretical curves were convoluted with 0.05 eV FWHM Gaussians to represent experimental broadening of possible high resolution experiments.
The temperature dependence of the ratio of the intensity of quasielastic scattering from relative to that for in an equimolar mixture, at equilibrium, given by Eq. (13). The input parameters used in the calculation are listed in Table I and were taken from Refs. 31 and 32. The variation is related to the temperature dependence of the ortho-para equilibrium, and the difference in the ortho and para contributions to the rotational fine structure.
The calculated quasielastic scattering spectrum of with decomposition into the contributions from ortho and para nuclear spin isomers at temperatures of 5, 70, and 300 K. Convolution with Gaussians of 50 meV FWHM was performed in order to show expected results from possible high resolution experiments.
The input parameters for calculation of the differential cross sections, sum rules, and centers of gravity of the quasielastic peaks of , , and HD (Refs. 31 and 32).
Calculated and observed sum rules and center of gravity energies of the quasielastic electron scattering peaks from , , and HD.
Calculated percent of the total peak area and contribution to the position of the center of gravity of the peak due to various excitation types in quasielastic electron scattering from , , and HD.
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