INFLUENCE OF FOREIGN GASES AT HIGH PRESSURES ON THE SELECTIVE REFLECTION FROM MERCURY VAPOR

1957 ◽  
Vol 35 (1) ◽  
pp. 114-121 ◽  
Author(s):  
H. L. Welsh ◽  
J. A. Galt
Keyword(s):  
Classical Theory ◽  
High Pressures ◽  
Mercury Vapor ◽  
Selective Reflection ◽  
Frequency Shifts ◽  
Absorbing Medium ◽  
Gas Density ◽  
Reflection Data ◽  
Collision Broadening

The influence of the foreign gases hydrogen, helium, nitrogen, and argon on the selective reflection from mercury vapor at 2537 Å was studied at pressures up to 1500 atm. The results were interpreted on the basis of the classical theory of reflection from an absorbing medium. The damping constant was found to vary linearly with foreign gas density as predicted by collision broadening theory. Frequency shifts and collision diameters determined from selective reflection data agree fairly well with values measured in absorption by other workers.

SELECTIVE REFLECTION FROM MERCURY VAPOR AT HIGH PRESSURES

1957 ◽  
Vol 35 (1) ◽  
pp. 98-113 ◽  
Author(s):  
H. L. Welsh ◽  
J. A. Galt
Keyword(s):  
Oscillator Strength ◽  
Classical Theory ◽  
Resonance Line ◽  
High Pressures ◽  
Mercury Vapor ◽  
Square Root ◽  
Special Design ◽  
Selective Reflection ◽  
Absorbing Medium ◽  
Reflection Maximum

Selective reflection from mercury vapor in the region of the 2537 Å resonance line was investigated at pressures up to 340 atm. using reflection cells of special design. The results were interpreted on the basis of the classical theory of reflection from an absorbing medium. By fitting calculated curves to the experimental reflection contours, values of the oscillator strength, f, and the damping constant, γ, were determined. The f values so obtained are density-dependent and at high pressures are approximately equal to one half the value for the free atom. As predicted by theory, the damping constant varies directly as the density of the atoms in the vapor. This result contradicts the earlier work of Welsh, Kastner, and Lauriston (1950) in which it was concluded that γ varies as the square root of the density. A subsidiary reflection maximum was observed at 2540 Å; it is attributed to Hg2 molecules which occur in relatively large concentrations at high densities. Some preliminary observations on the selective reflection at the 1850 Å resonance line were made up to 4.4 atm.

Physiological responses to exercise at 47 and 66 ATA

1984 ◽  
Vol 57 (4) ◽  
pp. 1055-1068 ◽  
Author(s):  
J. V. Salzano ◽  
E. M. Camporesi ◽  
B. W. Stolp ◽  
R. E. Moon
Keyword(s):  
High Pressures ◽  
Physiological Condition ◽  
Physiological Responses ◽  
Gas Mixture ◽  
Arterial Lactate ◽  
Gas Density ◽  
Physiological Dead Space ◽  
Surface Measurements ◽  
Alveolar Hypoventilation ◽  
Maximum Work

Five male volunteers served as subjects for exercise studies during three dives to pressures of 47 and 66 ATA while breathing gases containing 0.5 ATA PO2 and varying amounts of N2 and He. The inspired gas density ranged from 1.1 g/l (BTPS) at the surface to 17.1 g/l at the highest pressure. Dyspnea at rest and during exercise was evident in all divers and was predominantly inspiratory in nature. Despite the dyspnea, divers were able to perform work requiring an O2 consumption larger than 2 l/min STPD at each depth. Compared with surface measurements, moderate work at depth was associated with alveolar hypoventilation, arterial hypercapnia, very large physiological dead space, and higher levels of arterial lactate and signs of simultaneous respiratory and metabolic acidosis. The increase of ventilation that accompanies the onset of acidemia at the surface was not present at depth. Acidemia at depth was more severe, and its onset occurred at lesser work rates than at 1 ATA. No large differences could be ascertained when a variety of responses obtained with inspired gas having a density of 7.9 g/l at 47 ATA were compared with those obtained with an inspired gas density of 17.1 g/l at 66 ATA. It appears that the major impact of the environment on the physiological responses to work was almost fully manifested at a pressure of 47 ATA with a He-O2 gas mixture. It is cautioned that maximum work tolerance may be an insufficient assessment of the physiological condition of a diver exposed to these high pressures.

The Lithoprobe Abitibi-Grenville transect: two billion years of crust formation and recycling in the Precambrian Shield of Canada

2000 ◽  
Vol 37 (2-3) ◽  
pp. 459-476 ◽  
Author(s):  
John Ludden ◽  
Andrew Hynes
Keyword(s):  
Cross Sections ◽  
High Pressures ◽  
Significant Proportion ◽  
Superior Province ◽  
Crust Formation ◽  
Entire Cross Section ◽  
Grenville Province ◽  
Seismic Reflection Data ◽  
Precambrian Shield ◽  
Reflection Data

We summarize the results of Lithoprobe studies in the Neoarchean southeastern Superior Province and the Mesoproterozoic Grenville Province, in the southeastern Precambrian Shield of Canada, through two composite cross-sections based on seismic reflection data, which define dramatically different styles of crust formation and tectonic accretion in the Neoarchean and Mesoproterozoic. In the Neoarchean, the structures at the surface are steep, with discontinuous and flatter structures at depth, much of the crust appears to be juvenile, and the predominant process of crustal growth is inferred to have been subduction-accretion of primitive crust in a prograding arc system. In the Mesoproterozoic, surface structures are shallow and the seismic character of the crust is continuous over the entire cross-section. Archean parautochthonous rocks and reworked Archean crust comprise a very significant proportion of the preserved crust in the Mesoproterozoic and provided the backstop to the Grenvillian orogeny, resulting in the exhumation of crustal rocks formed at high pressures. Preservation of Neoarchean crust, including a thickened lithosphere in the Superior Province, in contrast to its general destruction in younger orogens, may well relate to a unique thermal regime at this time on Earth.

Surface-Enhanced Raman Spectroscopy from Colloids at High Pressures

1992 ◽  
Vol 289 ◽  
Author(s):  
Michael Bradley ◽  
John Krech ◽  
Shlomo Efrima
Keyword(s):  
High Pressures ◽  
Colloidal Suspension ◽  
Blue Shift ◽  
Surface Enhanced Raman Spectroscopy ◽  
Sers Spectrum ◽  
Frequency Shifts ◽  
Pressure Surface ◽  
Surface Enhanced ◽  
Anisic Acid ◽  
Surface Enhanced Raman

AbstractHigh pressure surface enhanced Raman (SERS) spectra are reported for a highly dense silver colloidal suspension, termed a MEtal Liquid-Like Film or MELLF. Comparison is made with the SERS spectrum of a dilute organosol. Raman signals due to adsorbed molecules and the solvent dichloromethane reveal appreciable frequency shifts as the colloidal environment is influenced by temperature, pressure, and packing. The C-Cl stretch of neat dichloromethane near 705 cm−1 shifts 1.7 cm −1 blue in a MELLF. Raman signals due to the adsorbed anisic acid in MELLFs blue shift about 2 cm −1 as 4 kilobars of pressure are applied; the solvent peaks shift blue only about 1 cm −1. Temperature influences the MELLF in two ways: desorption of anisic acid and formation of agglomerated particles.

Pressure shifts in the vibrational Raman spectra of hydrogen and deuterium, 315–85 K

1978 ◽  
Vol 56 (8) ◽  
pp. 1102-1108 ◽  
Author(s):  
E. C. Looi ◽  
J. C. Stryland ◽  
H. L. Welsh
Keyword(s):  
Standard Deviation ◽  
Raman Spectra ◽  
Rotational Level ◽  
The Other ◽  
Dispersion Forces ◽  
Temperature Dependent ◽  
Vibrational Coupling ◽  
Frequency Shifts ◽  
Linear Coefficient ◽  
Gas Density

The Raman frequencies of the Q(J) lines of the fundamental Raman bands of compressed H2 and D, were measured with a standard deviation of ±0.02 cm−1 at gas densities from 10 to 100 amagat at several temperatures in the range 315 to 85 K. The frequency shifts are negative and linear in the gas density; they range up to −1.2 cm−1 for H2 and −0.7 cm−1 for D2. The linear coefficient for the Q(J) line has the form, ai + ac(nJ/n), where nJ/n is the fractional population of the rotational level, J, and ai and ac are constants independent of J. The constant ai is strongly temperature-dependent and is interpreted as the vibrational shift due to isotropic dispersion and overlap forces. On the other hand, ac is practically temperature-independent and is believed to arise from vibrational coupling through dispersion forces.

Collision Broadening and Shift of the 535.0 nm Tl Line Accompanying the Photodissociation of Thallium Iodide Perturbed by Noble Gases Part II: Effects due to He, Ne and Ar

1981 ◽  
Vol 36 (8) ◽  
pp. 807-812 ◽  
Author(s):  
E. Lisicki ◽  
A. Bielski ◽  
J. Szudy
Keyword(s):  
Noble Gases ◽  
Van Der Waals ◽  
Half Width ◽  
Line Profiles ◽  
Gas Density ◽  
Lennard Jones ◽  
Fabry Perot ◽  
Collision Broadening ◽  
Helium Neon

Abstract The broadening and shift of the 535.0 nm thallium line resulting from the photodissociation of thallium iodide perturbed by helium, neon and argon were investigated at low densities using a photoelectric Fabry-Perot interferometer. The Doppler and collision broadening components of the line profiles have been determined. Linear variations of both the Lorentzian half-width and the shift of the line with the perturbing gas density were found and interpreted in terms of Van der Waals and Lennard-Jones potentials.

Selective reflection from high-pressure mercury vapor

1980 ◽  
Vol 21 (1) ◽  
pp. 77-81 ◽  
Author(s):  
M. Gröbel ◽  
W. Heering
Keyword(s):  
High Pressure ◽  
Mercury Vapor ◽  
Selective Reflection

scholarly journals THERMODYNAMIC QUANTITIES AT HIGH PRESSURES IN THE i AND θ PHASES OF SOLID NITROGEN DEDUCED BY RAMAN FREQUENCY SHIFTS FOR THE INTERNAL MODES IN LITERATURE

2013 ◽  
Vol 27 (09) ◽  
pp. 1350035 ◽  
Author(s):  
H. YURTSEVEN ◽  
S. SARITAŞ
Keyword(s):  
Experimental Data ◽  
Thermal Expansion ◽  
Specific Heat ◽  
Pressure Dependence ◽  
Isothermal Compressibility ◽  
High Pressures ◽  
Raman Frequency ◽  
Thermodynamic Quantities ◽  
Frequency Shifts ◽  
Solid Nitrogen

The pressure dependence of the Raman frequencies of the internal modes is analyzed (T = 300 K ) for the phases i and θ of solid nitrogen using the experimental data from the literature. Through the mode Grüneisen parameter, the isothermal compressibility κT, thermal expansion αp and the specific heat Cp–Cv are calculated as a function of pressure using the Raman data in these phases. We obtain that the αp varies linearly with the (1/υ)(∂υ/∂P)T and also that the Cp–Cv varies linearly with the αp for N 2. Our results show that by means of the analysis given here, the αp, κT and Cp–Cv can be predicted from the Raman frequency shifts for the i and θ phases of solid nitrogen.

Human respiration at rest in rapid compression and at high pressures and gas densities

1983 ◽  
Vol 54 (1) ◽  
pp. 290-303 ◽  
Author(s):  
R. Gelfand ◽  
C. J. Lambertsen ◽  
R. Strauss ◽  
J. M. Clark ◽  
C. D. Puglia
Keyword(s):  
Flow Resistance ◽  
Gas Flow ◽  
High Pressures ◽  
Ambient Pressure ◽  
Elimination Rate ◽  
Progressive Increase ◽  
Respiratory Drive ◽  
Gas Density ◽  
Human Respiration ◽  
End Tidal

Ventilation (V), end-tidal PCO2 (PACO2), and CO2 elimination rate were measured in men at rest breathing CO2-free gas over the pressure range 1–50 ATA and the gas density range 0.4–25 g/l, during slow and rapid compressions, at stable elevated ambient pressures and during slow decompressions in several phases of Predictive Studies III-1971 and Predictive Studies IV-1975. Inspired O2 was at or near natural O2 levels during compressions and at stable high pressures; it was 0.5 ATA during decompressions. Rapid compressions to high pressures did not impair respiratory homeostasis. Progressive increase in pulmonary gas flow resistance due to elevation of ambient pressure and inspired gas density to the He-O2 equivalent of 5,000 feet of seawater was not observed to progressively decrease resting V, or to progressively increase resting PACO2. Rather, a complex pattern of change in PACO2 was seen. As both ambient pressure and pulmonary gas flow resistance were progressively raised, PACO2 at first increased, went through a maximum, and then declined towards values near the 1 ATA level. It is suggested that this pattern of PACO2 change results from interaction on ventilation of 1) increase in pulmonary resistance due to elevation of gas density with 2) increase in respiratory drive postulated as due to generalized CNS excitation associated with exposure to high hydrostatic pressure. There may be a similar interaction between increased gas flow resistance and increase in respiratory drive related to nitrogen partial pressure and the narcosis resulting therefrom.

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