Collection Angle Dependence of the Depolarization Ratio in Light-Scattering Experiments

Teboul, Victor; Godet, Jean Luc; Duff, Y. Le

doi:10.1366/0003702924125285

Cited by 19 publications

(10 citation statements)

References 6 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Deb et al . calculated the error in the measured depolarization ratio due to this finite collection angle and later Teboul et al . refined the model for larger solid angles.…”

Section: Methodology and Theoretical Aspectsmentioning

confidence: 99%

Accurate depolarization ratio measurements for all diatomic hydrogen isotopologues

James

Schlösser

Fischer

et al. 2013

J Raman Spectroscopy

View full text Add to dashboard Cite

The Raman depolarization ratios for individual Q1(J”) branch lines of all diatomic hydrogen isotopologues – H2, HD, D2, HT, DT, and T2 – were measured, for all rotational levels with population larger than 1/100 relative to the Boltzmann maximum at room temperature. For these measurements, the experimental setup normally used for the monitoring of the tritiated hydrogen molecules at KArlsruhe TRItium Neutrino experiment was adapted to optimally control the excitation laser power and polarization, and to precisely define the Raman light collection geometry. The measured Raman depolarization values were compared to theoretical values, which are linked to polarizability tensor quantities. For this, the ‘raw data’ were corrected taking into account distinct aspects affecting Raman depolarization data, including (1) excitation polarization impurities; (2) extended Raman excitation volumes; and (3) Raman light collection over finite solid angles. Our corrected depolarization ratios of the hydrogen isotopologues agree with the theoretical values (based on ab initio quantum calculations by R.J. LeRoy, University of Waterloo, Canada) to better than 5% for nearly all of the measured Q1(J”) lines, with 1σ confidence level. The results demonstrate that reliable, accurate Raman depolarization ratios can be extracted from experimental measurements, which may be substantially distorted by excitation polarization impurities and by geometrical effects. Copyright © 2013 John Wiley & Sons, Ltd.

show abstract

“…Deb et al . calculated the error in the measured depolarization ratio due to this finite collection angle and later Teboul et al . refined the model for larger solid angles.…”

Section: Methodology and Theoretical Aspectsmentioning

confidence: 99%

Accurate depolarization ratio measurements for all diatomic hydrogen isotopologues

James

Schlösser

Fischer

et al. 2013

J Raman Spectroscopy

View full text Add to dashboard Cite

show abstract

“…The averaged SP0SA values (in brackets: standard deviation in the last digit) are compared to the theoretical values from LeRoy. [20] r obs r SP0SA r SP0SA H 2 J " #3 #7 #10 #3 #7 #10 average theory 1 .0241 (1) .0212 (1) .0285 (1) .0177 (1) .0189 (3) .0180 (1) .0182 (6) .0183 2…”

Section: Resultsmentioning

confidence: 99%

“…Bottom panel -difference between our (numerical) model and that of Teboul [6] (based on analytical expansion) for selected r SP0SA values as a function of the light collection angle θ max . components in our setup), the method which has been employed here allows the correction of the observed depolarization ratios without any additional measurements.…”

Section: Methodology For Correcting Observed Depolarization Ratiosmentioning

confidence: 99%

“…Note that integration limits have to be carefully considered, in order to properly account for (sequential) finite apertures along the light collection path. It therefore is of interest to compare the results of this model with that of Teboul et al [6] In Teboul's work, only scattered light originating from a point source is considered, passing through on-axis aligned apertures. This constitutes the sub-case in our model in which no z-integration is required (all light originates at z = 0), and an 'effective' circular aperture is defined via a single parameter θ max .…”

Section: Comparison To Previous Modelsmentioning

confidence: 99%

See 1 more Smart Citation

Evaluation method for Raman depolarization measurements including geometrical effects and polarization aberrations

Schlösser

James

Fischer

et al. 2013

J Raman Spectroscopy

View full text Add to dashboard Cite

In this article, we address the notoriously difficult problem to quantitatively link measured Raman depolarization values to theoretical polarizability tensor quantities, since quantum calculations do not incorporate experimental parameters. For this, we introduce a numerical model to calculate, for realistic experimental configurations, effective Raman line strength functions, f, which find their way into depolarization ratios, r. The model is based on interlinked integrations over the angles in the light collection path and a finite Raman source volume along the excitation laser beam. The model deals also with the conditional aperture parameters, associated with more than one optical component in the light collection path. Finally, we also can take into account polarization aberrations introduced by the sample cell windows. The procedure was fully tested for Raman depolarization spectra of selected hydrogen isotopologues. Distinct aspects affecting Raman depolarization data were validated, namely: (1) excitation polarization impurities; (2) extended Raman excitation volumes; (3) Raman light collection over finite solid angles; and (4) polarization aberrations introduced by optics in the light collection path. The correction of the experimental measurement data for the aforementioned effects resulted in depolarization ratios for the Q 1 (J ") Raman lines of H 2 and T 2 , which mostly differed by less than 5% from those obtained by quantum-calculations.

show abstract

“…However, in a realistic situation, a detector has finite dimensions, which modifies the actual values of the coefficients. 51 The isotropic spectrum cannot be measured directly, yet on the grounds of the equation set, Eq. (1), it can be determined as a weighted difference of the J V (ω) and J H (ω) spectral intensities.…”

Section: Collision-induced Isotropic Spectrum: General Consideratmentioning

confidence: 99%

Intermolecular polarizabilities in H2-rare-gas mixtures (H2–He, Ne, Ar, Kr, Xe): Insight from collisional isotropic spectral properties

Głaz

Bancewicz

Godet

et al. 2014

The Journal of Chemical Physics

View full text Add to dashboard Cite

The report presents results of theoretical and numerical analysis of the electrical properties related to the isotropic part of the polarizability induced by interactions within compounds built up of a hydrogen H2 molecule and a set of noble gas atoms, Rg, ranging from the least massive helium up to the heaviest xenon perturber. The Cartesian components of the collisional polarizabilities of the H2-Rg systems are found by means of the quantum chemistry methods and their dependence on the intermolecular distance is determined. On the basis of these data, the spherical, symmetry adapted components of the trace polarizability are derived in order to provide data sets that are convenient for evaluating collisional spectral profiles of the isotropic polarized part of light scattered by the H2-Rg mixtures. Three independent methods of numerical computing of the spectral intensities are applied at room temperature (295 K). The properties of the roto-translational profiles obtained are discussed in order to determine the role played by contributions corresponding to each of the symmetry adapted parts of the trace polarizability. By spreading the analysis over the collection of the H2-Rg systems, evolution of the spectral properties with the growing masses of the supermolecular compounds can be observed.

show abstract

Collection Angle Dependence of the Depolarization Ratio in Light-Scattering Experiments

Abstract: We have calculated, in a typical scattering experiment, the exact value of the intensity scattered by a sample for any value of the collection angle of the scattered beam and for different beam polarizations.

Cited by 19 publications

References 6 publications

Accurate depolarization ratio measurements for all diatomic hydrogen isotopologues

Accurate depolarization ratio measurements for all diatomic hydrogen isotopologues

Evaluation method for Raman depolarization measurements including geometrical effects and polarization aberrations

Intermolecular polarizabilities in H2-rare-gas mixtures (H2–He, Ne, Ar, Kr, Xe): Insight from collisional isotropic spectral properties

Contact Info

Product

Resources

About