scholarly journals The Dynamics of the S(1D)+H2/D2 Reactions at Low Temperature via Statistical Simulations

2020 ◽  
Vol 3 (1) ◽  
pp. 9-16
Author(s):  
Tomas Gonzalez-Lezana ◽  
Pascal Larrégaray ◽  
Laurent Bonnet
Keyword(s):  
Cross Sections ◽  
Quantum Model ◽  
Space Theory ◽  
Collisional Energy ◽  
Energy Regime ◽  
Phase Space Theory ◽  
The Mean ◽  
Statistical Approaches ◽  
Theoretical Results ◽  
Good Agreement

Two different statistical approaches, the statistical quantum model (SQM) and the mean potential phase space theory (MPPST), have been employed to calculate the integral cross sections for the reactive collisions between S(1D) and H2/ D2  in the low energy regime (below 0.3 eV collisional energy). The rate constant for the S(1D) + H2 → SH + H reaction has been also obtained and compared with previously reported experimental and theoretical results. The good agreement shows the capability of these two methods to study the dynamics of these complex-forming atom-diatom processes in the present energy regime.

scholarly journals Pulse Radiolysis Studies of Collisional Deexcitation of Ne(3P1) by H2

2015 ◽  
Vol 19 (1) ◽  
pp. 75-78
Author(s):  
Deba Bahadur Khadka
Keyword(s):  
Optical Absorption ◽  
Absorption Spectroscopy ◽  
Cross Sections ◽  
Pulse Radiolysis ◽  
Science And Technology ◽  
Optical Absorption Spectroscopy ◽  
Time Resolved ◽  
Collisional Energy ◽  
The Mean ◽  
Collisional Deexcitation

The cross sections for the deexcitation of Ne(3P1) by H2 have been measured as a function of the mean collisional energy in the range of 17.3-37.9 meV or in the temperature range from 134 K to 293 K using a pulse radiolysis method as combined with time-resolved optical absorption spectroscopy. The deexcitation cross sections are in the range of 2.1- 5.6 Å2 for Ne(3P1) and nearly constant or increase slightly with increasing the collisional energy.Journal of Institute of Science and Technology, 2014, 19(1): 75-78

Wear Mechanism of Ceramics and Surface Topography

1986 ◽  
Vol 108 (1) ◽  
pp. 9-15 ◽  
Author(s):  
T. Hisakado
Keyword(s):  
Cross Sections ◽  
Friction And Wear ◽  
Cross Sectional ◽  
Wear Rates ◽  
Contact Points ◽  
The Coefficient Of Friction ◽  
The Mean ◽  
New Criterion ◽  
Theoretical Results ◽  
Wear Tests

Assuming that harder asperities sliding on a flat surface were semicylindrical with the hemispherical ends, whose surface consisted of a series of spherical micro-asperities, effects of the number of contact points n, total area Sp of the cross-sections of grooves ploughed by harder asperities and depth of plastic zone on the coefficient of friction and wear for ceramics were theoretically analyzed. To verify theory, wear tests with various ceramic pins and a Si3N4 disk were carried out at a sliding speed of 1.63 m/s and under load of 0.98 N with no lubrication. The sizes of wear scratches on the worn surfaces were measured by means of a Talysurf and SEM photographs. The wear rates of the pins and Si3N4 disks increased with an increase in the mean cross-sectional area Sp/n of the scratches. This trend agreed with the theoretical results, which also showed that the Sp values were proportional to the wear rates. Theory also indicated the existence of a new criterion applicable to estimation of the wear rate.

Vibration of a Rotating Asymmetric Shaft Supported in Asymmetric Bearings

1968 ◽  
Vol 10 (3) ◽  
pp. 252-261 ◽  
Author(s):  
H. F. Black ◽  
A. J. McTernan
Keyword(s):  
Natural Frequencies ◽  
Equations Of Motion ◽  
Forced Vibrations ◽  
Variation Method ◽  
Approximate Theory ◽  
Cross Sectional ◽  
Mass Unbalance ◽  
The Mean ◽  
Theoretical Results ◽  
Good Agreement

The parametrically excited vibrations of this system with assumed small asymmetry of the shaft cross-section are discussed in terms of the motion of a symmetric shaft having the mean cross-sectional flexibility, and the equations of motion are solved by the approximate perturbation-variation method of Hsu. Both features yield a more lucid appreciation of the motions expected than previous treatments: in particular, simpler explicit expressions for unstable bounds are given and forced vibrations due to mass unbalance are discussed with greater facility. The practically important case of nearly coincident natural frequencies is examined. The theoretical results are compared with analogue computation: good agreement with the approximate theory is found even for quite large shaft asymmetry.

In-Plane Vibrations of Thick Circular Rings With T or I Cross Sections

1979 ◽  
Vol 46 (2) ◽  
pp. 470-472
Author(s):  
H. Lecoanet ◽  
J. Piranda
Keyword(s):  
Experimental Data ◽  
Eigenvalue Problem ◽  
Cross Section ◽  
Cross Sections ◽  
Rectangular Cross Section ◽  
Circular Rings ◽  
Theoretical Results ◽  
Good Agreement

This paper deals with the problem of eigenfrequencies and eigenvectors for rings whose cross section may be decomposed in basic rectangular cross sections. The solution is derived from a solution of the in-plane eigenvalue problem for rectangular cross-section thick rings. A good agreement between theoretical results and experimental data is obtained.

Beam-foil spectroscopy of oxygen in the wavelength region from 270 to 490 Å

1978 ◽  
Vol 56 (5) ◽  
pp. 508-516 ◽  
Author(s):  
Eric H. Pinnington ◽  
Keith E. Donnelly ◽  
J. Anthony Kernahan ◽  
David J. G. Irwin
Keyword(s):  
Satisfactory Agreement ◽  
Wavelength Region ◽  
Theoretical Predictions ◽  
The Mean ◽  
Theoretical Results ◽  
Beam Foil ◽  
Foil Technique ◽  
Good Agreement

We have used the beam-foil technique to study the spectrum of oxygen between 270 and 490 Å. We have measured the mean lives of the 3d2F, 3d4P, 3d4D, 3d′ 2D, 3d′ 2F, 4d4P, and 4d4D terms of O II, the 3s1P0, 3s3P0, 3S5P, 3s′ 3D, 3d3P, 3d3D, 3d3F, and 3d5P terms of O III, and the 3S2S, 3P2P0, and 3s4P0 terms of O IV. All cascade components are adequately explained. Good agreement is found with previous measurements in most cases, but significant discrepancies are found with some earlier results obtained using branches above 2000 Å. Generally satisfactory agreement is also found with theoretical predictions, although disagreement is found for several members of the 2p3–2p23d array in O II f-Values are computed for 18 individual lines, and compared with other experimental and theoretical results. Finally, we discuss briefly the f-value trends along the 2p23P–2p3s3P0 (O III), 2p21D–2p3s1P0 (O III), 2s2p24P–2s2p(3P0)3s4P0 (O IV), and 2p2P0–3s2S (O IV) isoelectronic sequences.

On the computation of dipole transitions in the HD molecule. Part II

1976 ◽  
Vol 54 (6) ◽  
pp. 672-679 ◽  
Author(s):  
L. Wolniewicz
Keyword(s):  
Ground State ◽  
Wave Functions ◽  
Nonadiabatic Coupling ◽  
Transition Moments ◽  
The Mean ◽  
Variational Wave Functions ◽  
Theoretical Results ◽  
Variational Wave ◽  
Electronic Ground ◽  
Good Agreement

The nonadiabatic coupling with Πu states in the electronic ground state of the HD molecule is discussed. Formulas are given that facilitate the evaluation of Πu contributions to the energies and transition moments. Numerical computations are performed for all ν ≤ 4 vibrational and J ≤ 4 rotational levels yielding the Πu and Σu nonadiabatic corrections. The variational wave functions are employed to compute the transition moments for the 0–ν bands with ν ≤ 4. The results are in good agreement with experimental data except in the case of the 0–ν band where the theoretical results are larger than the mean experimental moment by a factor of about 1.4.

scholarly journals Renormalised Perturbation Theory of Resonant Multiphoton Ionisation

1995 ◽  
Vol 48 (5) ◽  
pp. 835
Author(s):  
K Unnikrishnan
Keyword(s):  
Perturbation Theory ◽  
Cross Sections ◽  
Bound States ◽  
Resonance Region ◽  
Short Pulses ◽  
Total Cross Sections ◽  
Two Photon ◽  
Continuum States ◽  
The Mean ◽  
Good Agreement

Perturbation theory of multiphoton ionisation due to a classical electromagnetic field is modified to allow for intermediate resonances with bound states. Complex energies, generally associated with resonances, do not enter into this formalism. For a monochromatic field of frequency u, a constant ionisation rate can then be defined unambiguously and only such continuum states are excited which correspond to the absorption of energy in integral multiples of hu. As an application, differential and total cross sections for the two-photon ionisation of hydrogen, for frequencies below the n = 3 resonance region, are obtained in closed form. Existing data for generalised cross sections, calculated numerically using the complex coordinate method, are in good agreement with the present results. Finally, the mean fractional ionisation resulting from a pulse of finite duration is estimated on the basis of the associated power spectrum. For short pulses, the time dependence of ionisation exhibits a departure from that expected of a time-independent rate.

K-shell photoionization of Be-like nitrogen from the ground state: energies and Auger widths of the high-lying double-excited states for N IV

2018 ◽  
Vol 96 (11) ◽  
pp. 1183-1191
Author(s):  
Liang Liang ◽  
Chao Zhou
Keyword(s):  
Cross Sections ◽  
Ground State ◽  
Photoionization Cross Section ◽  
Coupling Scheme ◽  
Close Coupling ◽  
Resonance Energies ◽  
Auger Spectra ◽  
Distorted Wave Method ◽  
Theoretical Results ◽  
Good Agreement

The K-shell photoionization cross section of Be-like nitrogen (N IV) from the ground state is studied with the R-matrix and distorted-wave method for photon energies from 5.7 to 41.2 Ry. The close-coupling expansion includes 34 target states of N V with the 13 configurations in the LS-coupling scheme. The resonance energies, quantum defect and widths of 18 series of autoionization are determined from QB method and agree with these by cross sections. Our theoretical resonance energies and widths are compared with the existing experiments on the Auger spectra and other theoretical results. The results show that the calculated resonance energies are in rather good agreement with the experiment on the Auger spectra. For the autoionization width of some resonance states, good agreement is also found with recent theoretical results wherever available obtained using a saddle-point complex-rotation method.

scholarly journals Deexcitation Probabilities of Ne(3P2) by Kr for the Case E << D

1970 ◽  
Vol 24 ◽  
pp. 45-48
Author(s):  
Deba Bahadur Khadka
Keyword(s):  
Cross Section ◽  
Cross Sections ◽  
Chemical Society ◽  
Ionization Cross ◽  
Penning Ionization ◽  
Collisional Energy ◽  
Theoretical Investigations ◽  
Probability Calculation ◽  
The Mean ◽  
Made In

The deexcitation probability calculation of the total Penning ionization cross section for Ne(3P2) by Kr has been made in the region of the collisional energy from 18.5 to 38.1 meV. Considering the magnitude of the mean collisional energy with respect to D, the application of the analysis in the case E >> D is expected to be more appropriate than in the case E << D. Theoretical investigations of Ne(3P2) by Kr for the case E >> D are also needed.Keywords: metastable atoms, resonance atoms, deexcitation cross sections, pulse radiolysis, impact parameter.DOI: 10.3126/jncs.v24i0.2390Journal of Nepal Chemical Society Vol.24 Page 45-48

Infrared analysis of Glycine dissociation by MeV ions and keV electrons

2021 ◽  
Author(s):  
C A P da Costa ◽  
J A Souza-Corrêa ◽  
E F da Silveira
Keyword(s):  
Solar Wind ◽  
Cross Sections ◽  
Room Temperature ◽  
Stopping Power ◽  
Infrared Analysis ◽  
Absorbed Energy ◽  
Power Threshold ◽  
The Mean ◽  
Good Agreement ◽  
Electronic Stopping Power

Abstract Knowledge on amino acid's dissociation rates by solar wind is relevant for the study of biomaterial resistance in space. The radiolysis and sputtering of glycine by 1 keV electron beam and by 1.8 MeV H+, 1.5 MeV He+ and 1.5 MeV N+ ion beams are studied in laboratory, at room temperature. The column density decrease rates due to each beam are measured via infrared spectroscopy and destruction cross sections are determined. Present results stand in good agreement with those found in the literature and show that over five orders of magnitude, apparent destruction cross sections (which includes sputtering), σdap, are approximately proportional to the electronic stopping power, Se, that is (σdap ≈ a Se), where 1/a ≈ 120 eV/nm3. This value corresponds to the mean absorbed energy density necessary to dissociate (and/or eject) glycine; it also suggests that the stopping power threshold for molecular destruction is 23 keV μm−1. Assuming σdap = a Se for electron and ion projectiles, the half-life of pure α-glycine is estimated for the solar wind processing at 1 AU: about 10 days for protons or electrons and 40 days for He ions.

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