Reinvestigation of pressure broadening parameters at 60-GHz band and single 118.75GHz oxygen lines at room temperature

2003 ◽  
Vol 222 (2) ◽  
pp. 191-197 ◽  
Author(s):  
G.Yu. Golubiatnikov ◽  
M.A. Koshelev ◽  
A.F. Krupnov
Keyword(s):  
Room Temperature ◽  
60 Ghz ◽  
Pressure Broadening

Broadening of the Fine-Structure Raman Lines in Gaseous Oxygen

1971 ◽  
Vol 26 (10) ◽  
pp. 1639-1643
Author(s):  
S. Hess ◽  
H. F. P. Knaap
Keyword(s):  
Fine Structure ◽  
Relaxation Frequency ◽  
Collision Term ◽  
60 Ghz ◽  
Pressure Broadening ◽  
Gaseous Oxygen ◽  
Molecular Potential ◽  
Electronic Spin ◽  
Anti Stokes ◽  
Rayleigh Light

Abstract Due to the coupling between the rotational angular momentum and the electronic spin, the depolarized Rayleigh light scattered from gaseous oxygen shows Stokes and anti-Stokes satellites shifted by about 60 GHz. The broadening of these fine-structure Raman lines is investigated theoretically for high and medium pressures where the linewidth is determined by two contributions, one proportional and the other inversely proportional to the pressure, p. The linewidth in the pressure broadening region is given by a relaxation frequency which is obtained from the Waldmann-Snider collision term. The p-1 contribution to the linewidth is determined by the ratio of the second moment of the fine-structure freqencies (with respect to the center of the shifted line) and another relaxation frequency. Both relaxation frequencies are sensitive to the nonspherical part of the inter-molecular potential.

Collisional broadening and shifting of the pure rotational Raman lines S0(J = 0–4) of H2 at room temperature

1994 ◽  
Vol 72 (5-6) ◽  
pp. 186-192 ◽  
Author(s):  
M. P. Le Flohic ◽  
P. Duggan ◽  
P. M. Sinclair ◽  
J. R. Drummond ◽  
A. D. May
Keyword(s):  
Room Temperature ◽  
Intermolecular Forces ◽  
High Density ◽  
Linear Functions ◽  
Molecular Spectra ◽  
Pressure Broadening ◽  
Collisional Broadening ◽  
Normal Hydrogen ◽  
The Impact

The pressure broadening and shifting, of the S0(J = 0–4) pure rotational Raman lines of normal hydrogen, have been determined from 1 to 35 amagat units of density, at 29.8 °C. Over the range of densities explored, the width and shift of the lines are linear functions of the density. Our precise results may be reconciled with earlier measurements at higher densities by adding a term cubic in the density for the widths and quadratic in the density for the shifts. It is argued that the present results are safely within the impact regime and may be compared with calculations when they become available. The accuracy obtained is about 0.2 MHz per amagat [Formula: see text], for the broadening, and ranges from 0.1 to 0.3 MHz per amagat [Formula: see text] for the shifting coefficients. An analysis of the results indicate that it may be possible to combine the shifts of the pure vibrational and the pure rotational Raman lines to disentangle the contributions of the isotropic and anisotropic intermolecular forces to the perturbation of molecular spectra. Departures from linear broadening and shifting, at high density, are discussed.

scholarly journals Pressure broadening in the 2ν<sub>3</sub> band of methane and its implication on atmospheric retrievals

2008 ◽  
Vol 8 (17) ◽  
pp. 5061-5075 ◽  
Author(s):  
C. Frankenberg ◽  
T. Warneke ◽  
A. Butz ◽  
I. Aben ◽  
F. Hase ◽  
...  
Keyword(s):  
Room Temperature ◽  
Optimal Estimation ◽  
Atmospheric Methane ◽  
Laboratory Measurements ◽  
Pressure Broadening ◽  
Gas Cell ◽  
Constrained Least Squares ◽  
Spectroscopic Parameters ◽  
Scanning Imaging ◽  
Least Squares Approach

Abstract. N2-broadened half widths and pressure shifts were obtained for transitions in the 2ν3 methane band. Laboratory measurements recorded at 0.011 cm−1 resolution with a Bruker 120 HR Fouriertransform spectrometer were analysed from 5860 to 6185 cm−1. A 140 cm gas cell was filled with methane at room temperature and N2 as foreign gas at pressures ranging from 125 to 900 hPa. A multispectrum nonlinear constrained least squares approach based on Optimal Estimation was applied to derive the spectroscopic parameters by simultaneously fitting laboratory spectra at different ambient pressures assuming a Voigt line-shape. At room temperature, the half widths ranged between 0.030 and 0.071 cm−1 atm−1, and the pressure shifts varied from –0.002 to –0.025 cm−1 atm−1 for transitions up to J"=10. Especially for higher rotational levels, we find systematically narrower lines than HITRAN predicts. The Q and R branch of the new set of spectroscopic parameters is further tested with ground based direct sun Fourier transform infrared (FTIR) measurements where systematic fit residuals reduce by about a factor of 3–4. We report the implication of those differences on atmospheric methane measurements using high-resolution ground based FTIR measurements as well as low-resolution spectra from the SCanning Imaging Absorption SpectroMeter for Atmospheric ChartographY (SCIAMACHY) instrument onboard ENVISAT. We find that for SCIAMACHY, a latitudinal and seasonally varying bias of about 1% can be introduced by erroneous broadening parameters.

PRESSURE BROADENING OF THE ROTATIONAL RAMAN LINES OF SOME SIMPLE GASES

1966 ◽  
Vol 44 (4) ◽  
pp. 797-814 ◽  
Author(s):  
K. S. Jammu ◽  
G. E. St. John ◽  
H. L. Welsh
Keyword(s):  
Pressure Range ◽  
Room Temperature ◽  
Rotational Quantum Number ◽  
Quadrupolar Interaction ◽  
Pressure Broadening ◽  
Linear Dispersion ◽  
Exciting Line ◽  
Impact Approximation ◽  
The Impact ◽  
Good Agreement

Self-broadening of the rotational Raman lines of O2, N2, CO2, and CO, and foreign-gas broadening of O2 and N2 by He and Ar were measured in the pressure range from 7 to 43 atm at room temperature. Spectrograms were obtained with Hg 2 537 Å as exciting line and a reciprocal linear dispersion of 11.2 cm−1 per mm. In each case the broadening was found to be proportional to the pressure so that a broadening coefficient [Formula: see text] could be defined. The broadening coefficient shows a monotonie decrease with increasing rotational quantum number J. The values of [Formula: see text] for N2 and their variation with J are in good agreement with the values calculated theoretically by Van Kranendonk on the basis of quadrupolar interaction in the impact approximation.

Dependence of Intergranular Fracture on Boundary Topography and Cohesion

1973 ◽  
Vol 31 ◽  
pp. 150-151
Author(s):  
J. E. Doherty ◽  
A. F. Giamei ◽  
B. H. Kear ◽  
C. W. Steinke
Keyword(s):  
Grain Boundary ◽  
Room Temperature ◽  
Nickel Base Superalloy ◽  
Boundary Shear ◽  
Room Temperature Ductility ◽  
Solid Solution Matrix ◽  
Nickel Base ◽  
Solution Matrix ◽  
Different Levels ◽  
Base Superalloy

Recently we have been investigating a class of nickel-base superalloys which possess substantial room temperature ductility. This improvement in ductility is directly related to improvements in grain boundary strength due to increased boundary cohesion through control of detrimental impurities and improved boundary shear strength by controlled grain boundary micros true tures.For these investigations an experimental nickel-base superalloy was doped with different levels of sulphur impurity. The micros tructure after a heat treatment of 1360°C for 2 hr, 1200°C for 16 hr consists of coherent precipitates of γ’ Ni3(Al,X) in a nickel solid solution matrix.

Hepatocyte Alterations in Guinea Pigs FED Polychlorinated Biphenyls (PCBs), Dibenzodioxins (PCDD), AND DIBENZOFURANS (PCDF)

1982 ◽  
Vol 40 ◽  
pp. 56-57
Author(s):  
J. N. Turner ◽  
D. N. Collins
Keyword(s):  
Guinea Pigs ◽  
Room Temperature ◽  
Dose Group ◽  
Methyl Cellulose ◽  
Uranyl Acetate ◽  
Target Organ ◽  
Office Building ◽  
Lead Citrate ◽  
Control Groups ◽  
Cooling Fluid

A fire involving an electric service transformer and its cooling fluid, a mixture of PCBs and chlorinated benzenes, contaminated an office building with a fine soot. Chemical analysis showed PCDDs and PCDFs including the highly toxic tetra isomers. Guinea pigs were chosen as an experimental animal to test the soot's toxicity because of their sensitivity to these compounds, and the liver was examined because it is a target organ. The soot was suspended in 0.75% methyl cellulose and administered in a single dose by gavage at levels of 1,10,100, and 500mgm soot/kgm body weight. Each dose group was composed of 6 males and 6 females. Control groups included 12 (6 male, 6 female) animals fed activated carbon in methyl cellulose, 6 males fed methyl cellulose, and 16 males and 10 females untreated. The guinea pigs were sacrificed at 42 days by suffocation in CO2. Liver samples were immediately immersed and minced in 2% gluteraldehyde in cacadylate buffer at pH 7.4 and 4°C. After overnight fixation, samples were postfixed in 1% OsO4 in cacodylate for 1 hr at room temperature, embedded in epon, sectioned and stained with uranyl acetate and lead citrate.

Domain Formation in Synthetic Quartz

1971 ◽  
Vol 29 ◽  
pp. 156-157
Author(s):  
Joseph J. Comer
Keyword(s):  
Electron Beam ◽  
Room Temperature ◽  
Domain Formation ◽  
Synthetic Quartz ◽  
Transmission Electron ◽  
Black Spots ◽  
Diffraction Mode ◽  
Domain Boundaries ◽  
Kikuchi Lines ◽  
Straight Lines

Domains visible by transmission electron microscopy, believed to be Dauphiné inversion twins, were found in some specimens of synthetic quartz heated to 680°C and cooled to room temperature. With the electron beam close to parallel to the [0001] direction the domain boundaries appeared as straight lines normal to <100> and <410> or <510> directions. In the selected area diffraction mode, a shift of the Kikuchi lines was observed when the electron beam was made to traverse the specimen across a boundary. This shift indicates a change in orientation which accounts for the visibility of the domain by diffraction contrast when the specimen is tilted. Upon exposure to a 100 KV electron beam with a flux of 5x 1018 electrons/cm2sec the boundaries are rapidly decorated by radiation damage centers appearing as black spots. Similar crystallographio boundaries were sometimes found in unannealed (0001) quartz damaged by electrons.

A Liquid Nitrogen Cooled Stage for STEM

1974 ◽  
Vol 32 ◽  
pp. 444-445
Author(s):  
Louis T. Germinario
Keyword(s):  
Electron Microscope ◽  
High Resolution ◽  
Liquid Nitrogen ◽  
Room Temperature ◽  
Objective Lens ◽  
Thermal Drift ◽  
Specimen Holder ◽  
Resolution Capability ◽  
Focal Position

A liquid nitrogen stage has been developed for the JEOL JEM-100B electron microscope equipped with a scanning attachment. The design is a modification of the standard JEM-100B SEM specimen holder with specimen cooling to any temperatures In the range ~ 55°K to room temperature. Since the specimen plane is maintained at the ‘high resolution’ focal position of the objective lens and ‘bumping’ and thermal drift la minimized by supercooling the liquid nitrogen, the high resolution capability of the microscope is maintained (Fig.4).

Cryogenic atomic force microscopy

1991 ◽  
Vol 49 ◽  
pp. 54-55
Author(s):  
K. A. Fisher ◽  
M. G. L. Gustafsson ◽  
M. B. Shattuck ◽  
J. Clarke
Keyword(s):  
Room Temperature ◽  
Rapid Freezing ◽  
Cryogenic Temperatures ◽  
Soft Or ◽  
Electrically Conductive ◽  
Force Microscopy ◽  
Flexible Molecules ◽  
Advantages And Disadvantages ◽  
Atomic Force ◽  
Chemical Perturbation

The atomic force microscope (AFM) is capable of imaging electrically conductive and non-conductive surfaces at atomic resolution. When used to image biological samples, however, lateral resolution is often limited to nanometer levels, due primarily to AFM tip/sample interactions. Several approaches to immobilize and stabilize soft or flexible molecules for AFM have been examined, notably, tethering coating, and freezing. Although each approach has its advantages and disadvantages, rapid freezing techniques have the special advantage of avoiding chemical perturbation, and minimizing physical disruption of the sample. Scanning with an AFM at cryogenic temperatures has the potential to image frozen biomolecules at high resolution. We have constructed a force microscope capable of operating immersed in liquid n-pentane and have tested its performance at room temperature with carbon and metal-coated samples, and at 143° K with uncoated ferritin and purple membrane (PM).

Sign in / Sign up

Export Citation Format

Share Document