Herman–Wallis factor to improve thermometric accuracy of vibrational coherent anti-Stokes Raman spectra of H2

Marrocco, Michele

doi:10.1016/j.proci.2008.06.045

Cited by 18 publications

(38 citation statements)

References 31 publications

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“…The physical analysis shows that the two factors still in use among CARS users are in contradiction with each other. The incompatibility was never realized until very recently, [15,16] and here the comparison has been pushed further to support the introduction of a third HW factor that is more faithful to the complex physics of the problem. [29] This entails the changes of the polarizability components with the molecular size (which coincides with the oscillating internuclear distance in case of diatomics).…”

Section: Discussionmentioning

confidence: 79%

“…[24] The result provides explicit evidence that the Q-branch Raman cross section is sensibly modified and, as a consequence, it is no surprise that important deviations should be detected in CARS spectra. [15,16] If hydrogen is the best candidate to facilitate the most striking contrast between optical responses with and without vibration-rotation interaction, heavier molecules with greater moments of inertia have also been examined in this work. Nitrogen is a proper choice since it is widely used in CARS spectroscopy and, at the same time, is sufficiently heavy.…”

Section: Discussionmentioning

confidence: 99%

“…[10,13] Indeed, the temperature-excess measured with the old HW factors is now understood as the result of the smaller values of the old vibration-rotation couplings in comparison with F TB (J). [16] Apart from these initial applications of Eqn (10), its potential is still new among CARS users. It therefore appears reasonable to show the detailed calculation not included in previously published works.…”

Section: Analysis Of New Q-branch Hw Factorsmentioning

confidence: 99%

“…It therefore appears reasonable to show the detailed calculation not included in previously published works. [15,16] After some rearrangement, the result will also be adapted for the most known CARS molecule, that is N 2 .…”

Section: Analysis Of New Q-branch Hw Factorsmentioning

confidence: 99%

“…In particular, different authors make use of contradictory solutions of Eqn (1), [10 -14] and the confusion has persisted for years, even though CARS spectroscopy can boast numerous successful applications. [3] The unresolved question has lately been brought out in reference to a method capable of sorting out the most reliable Q-branch HW factor, [15,16] and although the problem has arisen for H 2 , its consequences for other molecules might attract attention. For this reason, it seems useful to examine in detail the physical elements inherent in the Q-branch HW factors appearing in the Raman cross section for detection geometries typical of CARS measurements.…”

Section: Introductionmentioning

confidence: 99%

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Comparative analysis of Herman‐Wallis factors for uses in coherent anti‐Stokes Raman spectra of light molecules

Marrocco

2009

J Raman Spectroscopy

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The cross section of Raman processes involving light molecules takes into account the unavoidable coupling between rotational and vibrational modes. This coupling is quantified by the Herman-Wallis (HW) factor and its use was recently criticized in view of the known thermometric application of vibrational spectra of coherent antiStokes Raman scattering (CARS) of hydrogen. Following this line of research, this paper addresses the physical limitations of the HW factors employed ordinarily in Q-branch CARS measurements. Furthermore, new determinations of the vibration-rotation coupling are considered. These are based on a more realistic scenario consisting of anharmonic oscillations and polarizability variations during vibration. Numerical examples for fundamental diatomics, namely H 2 and N 2 , are given throughout the text. It is found that, as expected, the Raman cross section of H 2 is strongly dependent on the HW factor and the consequent correction to CARS line intensities is of the order of 10% or greater. Surprisingly, the analysis suggests that N 2 spectral data are also affected, to a certain extent, by the new HW factors. Usually, this correction is completely disregarded, but under the new understanding of the vibration-rotation coupling, Q-branch CARS lines of N 2 are predicted to undergo variations between 1 and 5% for rotational levels that are sufficiently populated at temperatures of interest for CARS studies. Oxygen is also prone to vibration-rotation corrections and is finally shown as an example between the two limits of hydrogen and nitrogen.

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Section: Discussionmentioning

confidence: 79%

Section: Discussionmentioning

confidence: 99%

Section: Analysis Of New Q-branch Hw Factorsmentioning

confidence: 99%

Section: Analysis Of New Q-branch Hw Factorsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Comparative analysis of Herman‐Wallis factors for uses in coherent anti‐Stokes Raman spectra of light molecules

Marrocco

2009

J Raman Spectroscopy

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High‐resolutionRaman Spectroscopy of Gases

Weber

2011

Handbook of High‐resolution Spectroscopy

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A review of high‐resolution Raman spectroscopy of gases, including spontaneous, incoherent Raman spectroscopy, as well as of nonlinear techniques for coherent anti‐Stokes scattering (CARS), stimulated Raman gain (SRG) and stimulated Raman loss (SRL) spectroscopy, and photoacoustic Raman spectroscopy (PARS) in the frequency domain is presented. Femtosecond degenerate four‐wave mixing spectroscopy (Fs‐DFWM) and Raman‐induced polarization spectroscopy (RIPS) in the time domain are discussed. Also treated are the broadenings of Raman lines due to the Doppler and pressure effects. Basic theoretical notions and working equations for the analysis of highly resolved spectra are presented. Examples are drawn from the literature to illustrate the respective advantages and disadvantages of the various techniques. The interplay between high‐resolution Raman spectroscopy, infrared spectroscopy, and ab initio computational schemes is illustrated. The article concludes with an overall assessment of the respective advantages and disadvantages of the methods used in high‐resolution Raman spectroscopy.

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CARS Spectroscopy

Marrocco

2010

Handbook of Combustion

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Coherent anti‐Stokes Raman scattering (CARS) is known for its potential for accurate thermometric measurements. In this chapter, an explanation is provided of how the unrivaled sensitivity of CARS spectral lines to temperature combines with chemical selection, high spectral intensities, directionality of the signal, spatial resolution and short integration times. These advantages contrast with the complexity of the technique involving the use of more than one laser beam. Details are presented of the fundamental principles and some typical examples are given. Uses related to species detection in current research and perspectives are also briefly outlined.

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Herman–Wallis factor to improve thermometric accuracy of vibrational coherent anti-Stokes Raman spectra of H2

Cited by 18 publications

References 31 publications

Comparative analysis of Herman‐Wallis factors for uses in coherent anti‐Stokes Raman spectra of light molecules

Comparative analysis of Herman‐Wallis factors for uses in coherent anti‐Stokes Raman spectra of light molecules

High‐resolutionRaman Spectroscopy of Gases

CARS Spectroscopy

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