The lattice modes of CS2 and neutron scattering selection rules

1981 ◽  
Vol 59 (1) ◽  
pp. 122-129 ◽  
Author(s):  
G. S. Pawley ◽  
G. Dolling ◽  
B. M. Powell ◽  
B. H. Torrie
Keyword(s):  
Neutron Scattering ◽  
Inelastic Neutron Scattering ◽  
Theoretical Work ◽  
Inelastic Neutron ◽  
Experimental Conditions ◽  
Selection Rules ◽  
Lattice Mode ◽  
Special Points ◽  
Lattice Modes ◽  
Good Agreement

A very simple model for the lattice dynamics of CS2 is presented. This model is fully stable for a unit cell distorted by no more than 2% from the measured cell and gives good agreement with lattice mode frequencies obtained from optical studies. Coulombic forces appear not to be important for this structure. The molecular motion in modes for all the special points in the Brillouin zone is described through the use of an explicit notation. The group theoretical work of Grout el al. is extended to give the full selection rules for coherent inelastic neutron scattering. These rules show that certain modes can be measured with minimal interference from scattering from modes of different symmetry when certain experimental conditions are adopted, and therefore these rules will be of great use in the neutron scattering studies now in progress.

scholarly journals Investigations of Hydrocarbon Species on Solid Catalysts by Inelastic Neutron Scattering

2020 ◽  
Author(s):  
Longfei Lin ◽  
Qingqing Mei ◽  
Xue Han ◽  
Stewart F. Parker ◽  
Sihai Yang
Keyword(s):  
Heterogeneous Catalysis ◽  
Neutron Scattering ◽  
Vibrational Spectroscopy ◽  
Inelastic Neutron Scattering ◽  
Inelastic Neutron ◽  
Surface Species ◽  
Catalytic Systems ◽  
Selection Rules ◽  
Solid Catalysts ◽  
Wide Range

Abstract The status of surface species on solid catalysts during heterogeneous catalysis is often mysterious. Investigations of these surface species are crucial to deconvolute the reaction network and design more efficient catalysts. Vibrational spectroscopy is a powerful technique to study the interactions between surface species and the catalysts and infrared (IR) and Raman spectroscopies have been widely applied to study reaction mechanisms in heterogeneous catalysis. However, IR/Raman spectra are difficult to model computationally and important vibrational modes may be IR-, Raman- (or both) inactive due to restrictions by optical selection rules. Inelastic neutron scattering (INS) is another form of vibrational spectroscopy and relies on the scattering of neutrons by the atomic nucleus. A consequence of this is that INS is not subject to any optical selection rules and all vibrations are measurable in principle. INS spectroscopy has been used to investigate surface species on catalysts in a wide range of heterogeneous catalytic reactions. In this mini-review, we focus on applications of INS in two important fields: petrochemical reactions and C1 chemistry. We introduce the basic principles of the INS technique, followed by a discussion of its application in investigating two key catalytic systems: (i) the behaviour of hydrocarbons on metal-oxide and zeolite catalysts and (ii) the formation of hydrocarbonaceous species on methane reforming and Fischer–Tropsch catalysts. The power of INS in studying these important catalytic systems is demonstrated.

Impulse approximation neutron scattering from N2

1995 ◽  
Vol 73 (11-12) ◽  
pp. 772-778 ◽  
Author(s):  
R. A. Cowley ◽  
M. P. Zinkin ◽  
R. S. Eccleston ◽  
A. C. Evans ◽  
M. J. Harris
Keyword(s):  
Neutron Scattering ◽  
Inelastic Neutron Scattering ◽  
Impulse Approximation ◽  
Inelastic Neutron ◽  
Vibrational Modes ◽  
Excitation Energies ◽  
Energy Transfers ◽  
Molecular Excitation ◽  
The Individual ◽  
Good Agreement

We present the results of a detailed investigation of the inelastic neutron scattering from diatomic N2, at wave-vector transfers in the range Q = 20–100 Å−1 (1Å = 10−10 m). At intermediate Q, the scattering shows structure arising from the vibrational modes of the molecule, while at large Q the scattering is well described by the impulse approximation for the individual atoms, despite the fact that the corresponding energy transfers are considerably less than the maximum molecular excitation energies. We find good agreement for all Q with a calculation incorporating the internal rotational and vibrational modes of the molecule explicitly.

Inelastic neutron scattering from low-frequency (00q) longitudinal lattice modes in graphite-SbCl5intercalation compounds

1984 ◽  
Vol 29 (4) ◽  
pp. 2138-2141 ◽  
Author(s):  
P. C. Eklund ◽  
V. Yeh ◽  
H. G. Smith ◽  
R. Nicklow ◽  
R. Al-Jishi ◽  
...  
Keyword(s):  
Neutron Scattering ◽  
Inelastic Neutron Scattering ◽  
Low Frequency ◽  
Inelastic Neutron ◽  
Lattice Modes
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