Multiphoton absorption of broad-band CO2 laser radiation by SF6

Alimpiev, S. S.; Fuß, Werner; Kompa, K. L.; Schwab, C.; Wan, Chongyi

doi:10.1007/bf00697513

Cited by 16 publications

(6 citation statements)

References 24 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…They should be higher than the values reported in the literature [38] for the collisionless regime. Such results are expected [30,[34][35][36][37]. σ a2 , however, is a similar quantity, but averaged over the high pressure range.…”

Section: The Bulk Rotational Cross Sections σ (A)supporting

confidence: 63%

“…The σ a is actually the enhanced absorption cross section for specific incident laser energy (E i ), dependent on experimental conditions. Due to strong σ a dependence [34][35][36][37] on incident laser parameters (laser band-width, pulse shape, etc) and the gas pressure conditions under which rotational processes are investigated (collisionless or collisional regime), this quantity usually cannot be taken from the literature. Hence, σ a requires independent estimation for the particular experimental conditions.…”

Section: The Bulk Rotational Cross Sections σ (A)mentioning

confidence: 99%

See 1 more Smart Citation

A Simple Detector for Measuring the Density of Air Using an α-Ray Source

Matsumoto

Toyooka

1993

Jpn. J. Appl. Phys.

View full text Add to dashboard Cite

The IR pulsed photoacoustic method was used to investigate rotational relaxation processes in MPA. We have examined the bulk rotational relaxation times (t R ) and the bulk rotational relaxation cross sections (σ R ), related to R-R and R-T relaxation mechanisms. The saturation intensities for SF 6 gas molecules have been measured in the gas mixtures with CH 4 (buffer) molecules, at constant SF 6 gas pressure (0.47 mbar) and variable CH 4 gas pressure (1-140 mbar), using the 10P(16) CO 2 laser line in the fluences range 0.1-0.7 J cm −2 . It has been found that for proper investigation of the rotational relaxation processes, the buffer gas pressure range must be divided into two parts: the low pressure range (0-20 mbar) and the high pressure range (20-140 mbar), according to the behaviour of the saturation intensities versus buffer gas pressure. Consequently, two different sets of values for rotational relaxation parameters are obtained. The found step-function behaviour for σ R shows that the rotational hole-filling effect during MPA only dominates at low buffer gas pressure (p CH 4 20 mbar). At higher buffer gas pressures (between 20-140 mbar) collisional deactivation takes place. We also derive the enhanced absorption cross sections for absorbing SF 6 gas molecules from the measured saturation intensities data (at zero buffer gas pressure) confirming the expectation that the enhanced absorbing cross sections are not only a function of laser fluence and buffer gas pressure, but are very strongly dependent on laser beam parameters, too.

show abstract

Section: The Bulk Rotational Cross Sections σ (A)supporting

confidence: 63%

Section: The Bulk Rotational Cross Sections σ (A)mentioning

confidence: 99%

A Simple Detector for Measuring the Density of Air Using an α-Ray Source

Matsumoto

Toyooka

1993

Jpn. J. Appl. Phys.

View full text Add to dashboard Cite

show abstract

“…The absolute values are, however, notably different but the experimental conditions also (for example, the SF6 pressure is 0.23 mBar in the work of Ref. 4). It can be underlined that the broad band excitation has some similarity with multifrequency excitations such as those of Refs.…”

Section: Or Inmentioning

confidence: 95%

“…In the most general way, the molecular MPA cross section can be expressed as the following: o(cp, v, ft, Vh) (4) q is the fluence exciting the molecule (J/cm2); v is the linecenter frequency of the laser emission; ft is the electric field temporal evolution for a normalized fluence (obviouslyft is equivalent to the complex spectral distribution f,, of the electric field); //)i is the initial rovibrational state of the molecule. tr depends on the position of the molecule in the cell through its fluence dependence.…”

Section: Analysis Of Experimental Datamentioning

confidence: 99%

See 1 more Smart Citation

Multiphoton Absorption of ¹²CF₃I,¹³CF₃I, CF₃Br and SF₆ by a HighPressure CO₂ Laser

1986

View full text Add to dashboard Cite

An investigation of the IR multiphoton absorption (MPA) of 12CF3I, 13CF3I, CF3Br and SF6, excited in cell by a 10 Bars TE CO2 laser is reported. The spatial, spectral and temporal characteristics of the laser emission versus the grating position have been carefully investigated. The main result is that the peaks observed in the different MPA spectra are undoubtedly correlated to the gain curve of the laser and not to the fine molecular spectroscopy.This result is discussed in comparison with published similar works. The most likely explanation involves a laser bandwidth effect associated with a background of weak but rather dense resonances (typical spacing of 0.1–0.2cm−1). The MPA cross section of 13CF3I is about half that of 12CF3I pointing out the probable rôle of Fermi resonances.

show abstract

The Role of “Rotational Freezing” in the Polarisation‐Dependent Two‐Photon Excitation of Triply Degenerate Vibrations in Spherical‐Top‐Molecules

Ritze

1986

Annalen der Physik

View full text Add to dashboard Cite

A b s t r a c t . Under certain circumstances at low rotational temperatures the multiphoton excitation probabilities of vibrational-rotational levels in high-symmetric molecules do not depend on the rotational quantum numbers J and M of the initially populated levels. Then the rotation of the molecule as a whole is "frozen". This has the consequence that during the absorption process the photon spin is not transferred to the molecular rotation but to the molecular vibration. I n more detail the two-photon A,,(v = 0 ) -+ A,,(v = 2) transition in SF, at 944.5 cm-1 is theoretically studied: If the "average lifetime" in the intermediate (v = 1)-level is small compared with the effective molecular rotation period the considered transition is forbidden for circularly polarised light. Further the excitation process of the E,(v = 2) and F2,(v = 2) vibrational levels is investigated; it is discussed under which conditions i t is not necessary to consider the rotational degrees of freedom for a calculation of transition dipole moments. Die Rolle der ,,Rotationseinfrierung" bei der polarisationsabhangigen Zwei-Photonen-Anregung dreifach entarteter Schwingungn in kugelkreiselartigen Molekiilen I n h a l t s i i b e r s i c h t . Unter gewissen Umstanden hangen bei tiefen Rotationstemperaturen dieMehrphotonen-Anregungswahrscheinlichkeiten von Schwingungs-Rotations-Niveaus hochsymmetrischer Molekule nicht von den Rotationsquantenzahlen J und 41 der anfanglich thermisch besetzten Niveaus ab. Dann ist die R'otation des Molekiils als gmzes ,,eingefroren". Dies hat zur Folge, da13 wahrend des Absorptionsprozesses der Photonenspin nicht auf die Molekiilrotation sondern anf die Molekulschwingung ubertragen wird. Detaillierter wird der Zwei-Photonen-A,,(v = 0) + A,,(v = 2 ) -Ubergang in SF, bei 944,6 cm-1 theoretisch untcrsucht : Wenn die ,,mittlere Verweildauer" im ( t l = 1)-Zwischenniveau klein im Vergleich zur effektiven Molekulrotationsperiode ist, ist der betrachtete Ubergang fur zirkular polarisiertes Licht vorboten. Des weiteren wird der AnregungsprozeB der X,(v = 2)-sowie F2,(v = 2)-Schwingungsniveaus untersucht; es wird diskutiert, unter melchen Bedingungen die Rotationsfreiheitsgrade bei einer Berechnung der ubergangsdipolmomente nicht berucksichtigt zu werden brauchen. (0 = 0,1= 0) -(v = I, 1 = 1) $ ill -+ Jf L+ M + M + l @? -1 w -1 ) ( J -41)

show abstract

Multiphoton absorption of broad-band CO2 laser radiation by SF6

Cited by 16 publications

References 24 publications

A Simple Detector for Measuring the Density of Air Using an α-Ray Source

A Simple Detector for Measuring the Density of Air Using an α-Ray Source

Multiphoton Absorption of ¹²CF₃I,¹³CF₃I, CF₃Br and SF₆ by a HighPressure CO₂ Laser

The Role of “Rotational Freezing” in the Polarisation‐Dependent Two‐Photon Excitation of Triply Degenerate Vibrations in Spherical‐Top‐Molecules

Contact Info

Product

Resources

About

Multiphoton absorption of broad-band CO2 laser radiation by SF6

Cited by 16 publications

References 24 publications

A Simple Detector for Measuring the Density of Air Using an α-Ray Source

A Simple Detector for Measuring the Density of Air Using an α-Ray Source

Multiphoton Absorption of 12CF3I,13CF3I, CF3Br and SF6 by a HighPressure CO2 Laser

The Role of “Rotational Freezing” in the Polarisation‐Dependent Two‐Photon Excitation of Triply Degenerate Vibrations in Spherical‐Top‐Molecules

Contact Info

Product

Resources

About

Multiphoton Absorption of ¹²CF₃I,¹³CF₃I, CF₃Br and SF₆ by a HighPressure CO₂ Laser