Ultraviolet laser photodesorption of NO from condensed films: Translational and internal energy distributions

Natzle, W.; Padowitz, David F.; Sibener, S. J.

doi:10.1063/1.454255

Cited by 76 publications

(53 citation statements)

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“…Assuming that the NO + / (NO) 2 reaction occurs at the collision rate, we estimated that the concentration of (NO) 2 formed, when 4.7% NO/He mixture is added through RGI A at 161 K, is about 4%. This value is higher than that obtained in photodesorption experiments, 18 which may reflect the difference in the various desorption mechanisms. But, the high value also may be due to the large uncertainty in the (NO) 2 detection with studies using a TOF mass spectrometer, 18 because the ionization cross section and fragmentation probability for (NO) 2 are not known.…”

Section: Resultsmentioning

confidence: 70%

Reactivity of NO with Anionic Water Clusters A^-·(X₂O)_n (A = O, OX, O₂, and XO₂; X = D and H). Formation of (NO)₂ and N₂O₃ and Their Reactions

1996

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The reactivity of NO toward anionic water clusters, A -‚(X 2 O) n , A ) O, OX, O 2 , and XO 2 ; X ) D and H), at several temperatures within the range 157-298 K, and at helium buffer gas pressures between 0.28 and 0.43 Torr, was studied using a flow-tube apparatus. The O -‚(X 2 O) ne5 and O 2 -‚(X 2 O) ne3 clusters were observed to react quite efficiently with NO, and the rate constants for these reactions were determined. The observed rate constants for O 2 -‚(X 2 O) n show a positive temperature dependence. This observation is explained in terms of an energy barrier to the isomerization of the peroxy structural form, ONOO -‚(X 2 O) n , to the conventional nitrate anion structure, NO 3 -‚(X 2 O) n . For OX -‚(X 2 O) ne5 , no detectable reaction with NO was observed to occur. Evidence for formation of the NO dimer and N 2 O 3 in the flow-tube apparatus is presented. Under the flow-tube conditions employed, the N 2 O 3 species is found to react efficiently with OX -‚(X 2 O) ne5 , XO 2 -‚(X 2 O) ne4 and NO 2 -‚(X 2 O) ne2 via a ligand switching mechanism. The implications of these studies for atmospheric and environmental chemistry are briefly discussed.

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Section: Resultsmentioning

confidence: 70%

Reactivity of NO with Anionic Water Clusters A^-·(X₂O)_n (A = O, OX, O₂, and XO₂; X = D and H). Formation of (NO)₂ and N₂O₃ and Their Reactions

1996

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“…39͒ at 248 nm and cryogenic films on Ag͑111͒ at 220-270 nm. 11 The NO fragments have been reported to occur in rather highly excited rotational and vibrational states. Dimer dissociation in the gas phase at 193 nm 64-66 also showed substantial excitation of internal molecular degrees of freedom.…”

Section: Discussionmentioning

confidence: 99%

“…The phenomenon of trapping or caging prior to desorption has frequently been observed in several photodesorption experiments. [10][11][12][13] In those cases, internal state distributions after desorption normally exhibit two channels, one hot channel resulting from direct desorption and a second channel attributed to trapping with internal state distributions accommodated to the surface temperature.…”

Section: Introductionmentioning

confidence: 99%

Ultraviolet-laser induced desorption of NO from the Cr2O3(0001) surface: Involvement of a precursor state?

Wilde

Seiferth

Al‐Shamery

et al. 1999

The Journal of Chemical Physics

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A joint theoretical-experimental investigation of the lower bound states of the NO (X 2 Π)-Ar complex NO molecules interact with the Cr 2 O 3 (0001) surface to form a chemisorption bond of 1.0 eV. At higher coverages an additional more weakly bound species appears in thermal desorption spectra with a binding energy of 0.35 eV. By infrared spectroscopy the weakly adsorbed species is identified to be an unusually strong bound NO-dimer exhibiting a weak feature at 1857 cm Ϫ1 beside the chemisorbate absorption band at 1794 cm Ϫ1 . Laser induced desorption experiments performed at 6.4 eV are presented with main emphasis on the high coverage regime. The desorbing molecules are detected quantum state selectively using resonance enhanced multiphoton ionization. The desorbing molecules are strongly rotationally and vibrationally excited conform with a nonthermal excitation process. The velocity distributions of single rovibronic states of desorbing NO are bimodal and exhibit a strong coupling of rotation and translation. With increasing coverages an additional channel is observed appearing in the time-of-flight spectra of vЉϭ0 as smoothly increasing intensity at long flight times. The numeric values of these unusually long flight times are indicative for long residence times on the surface rather than small kinetic energies. The desorption efficiencies weakly depend on the concentration and vibrational state ranging from (2.0Ϯ0.3)ϫ10 Ϫ17 cm 2 at low coverages to (1.0Ϯ0.4)ϫ10 Ϫ17 cm 2 at high coverages for vЉϭ0. The intensity of the desorption signal per laser pulse only increases proportional to the chemisorbate coverage. The data are interpreted assuming the dimers to act as extrinsic precursors within the desorption process.

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“…Single shot time-of-flight molecular distributions measured following ultraviolet laser pulse excitation of surfaces have been found to obey modified Maxwellian velocity distributions upon conversions of surface thermal (absorbed) energy into molecular kinetic energy [105,106]. Photothermal desorption and ablation was reported for the system NO on Ag (111) [107]. Several advances in the spectroscopy of surfaces and adsorbates have been made using pyroelectric detection.…”

Section: B) Broader Thermal Analysismentioning

confidence: 97%

Photothermal applications to the thermal analysis of solids

Mandelis

1991

Journal of Thermal Analysis

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Major application of optically-induced thermal waves to the thermal and thermodynamic analysis of solids are reviewed. The spectrum of available techniques,from the conventional photoaeoustic detection to novel photothermal laser probing and frequency multiplexing is discussed, and their utilization for the measurement of thermophysical thermal transport-related parameters of solids is presented. These include the thermal diffusivity, effusivity, conductivity and specific heat. The ability of photothermal methods to perform thermal analysis on large classes of solids, including conducting and insulating bulk materials, crystals, layered porous and coated structures, thin films and inhomogeneous thermal profiles is highlighted. Finally, special capabilities of photothermal analysis, such as the monitoring of surface thermodynamic phenomena and phase transition studies, including high-Tc superconductors, are described in order to give a complete overview of the rich potential of photothermal-based methodologies.Exposure of a sample to radiation results in local heating due to absorption and subsequent thermalization of the incident radiation. The extent of absorption and the thermalized volume fraction depend on the interplay between the absorption profile and the thermal transport properties of the material under investigation. If the irradianee of the incident radiation is modulated harmonically or pulsed, an oscillatory or transient heat source, respectively, is generated in the sample. Thermal waves are thus created,

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Ultraviolet laser photodesorption of NO from condensed films: Translational and internal energy distributions

Abstract: Articles you may be interested inPhotodesorption of physisorbed molecules from a Ag(111) surface: The low photon energy threshold and the low translational temperature of desorbed molecules

Cited by 76 publications

References 50 publications

Reactivity of NO with Anionic Water Clusters A^-·(X₂O)_n (A = O, OX, O₂, and XO₂; X = D and H). Formation of (NO)₂ and N₂O₃ and Their Reactions

Reactivity of NO with Anionic Water Clusters A^-·(X₂O)_n (A = O, OX, O₂, and XO₂; X = D and H). Formation of (NO)₂ and N₂O₃ and Their Reactions

Ultraviolet-laser induced desorption of NO from the Cr2O3(0001) surface: Involvement of a precursor state?

Photothermal applications to the thermal analysis of solids

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Ultraviolet laser photodesorption of NO from condensed films: Translational and internal energy distributions

Abstract: Articles you may be interested inPhotodesorption of physisorbed molecules from a Ag(111) surface: The low photon energy threshold and the low translational temperature of desorbed molecules

Cited by 76 publications

References 50 publications

Reactivity of NO with Anionic Water Clusters A-·(X2O)n (A = O, OX, O2, and XO2; X = D and H). Formation of (NO)2 and N2O3 and Their Reactions

Reactivity of NO with Anionic Water Clusters A-·(X2O)n (A = O, OX, O2, and XO2; X = D and H). Formation of (NO)2 and N2O3 and Their Reactions

Ultraviolet-laser induced desorption of NO from the Cr2O3(0001) surface: Involvement of a precursor state?

Photothermal applications to the thermal analysis of solids

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Reactivity of NO with Anionic Water Clusters A^-·(X₂O)_n (A = O, OX, O₂, and XO₂; X = D and H). Formation of (NO)₂ and N₂O₃ and Their Reactions

Reactivity of NO with Anionic Water Clusters A^-·(X₂O)_n (A = O, OX, O₂, and XO₂; X = D and H). Formation of (NO)₂ and N₂O₃ and Their Reactions