On the relative importance of spin–spin and spin–rotation relaxation in gas phase NMR

1978 ◽  
Vol 69 (11) ◽  
pp. 4999-5005 ◽  
Author(s):  
Donald J. Kouri
Keyword(s):  
Gas Phase ◽  
Spin Rotation ◽  
Relative Importance

scholarly journals Boron abundances in diffuse interstellar clouds

2009 ◽  
Vol 5 (S268) ◽  
pp. 237-242
Author(s):  
Adam M. Ritchey ◽  
S. R. Federman ◽  
Y. Sheffer ◽  
D. L. Lambert
Keyword(s):  
Gas Phase ◽  
Massive Star ◽  
Galactic Halo ◽  
Galactic Disk ◽  
Cosmic Ray ◽  
Secondary Process ◽  
Relative Importance ◽  
Interstellar Clouds ◽  
Comprehensive Survey ◽  
Spiral Arm

AbstractWe present a comprehensive survey of B abundances in diffuse interstellar clouds from HST/STIS observations along 56 Galactic sight lines. Our sample is the result of a complete search of archival STIS data for the B II λ1362 resonance line, with each detection confirmed by the presence of absorption from other dominant ions at the same velocity. The data probe a range of astrophysical environments including both high-density regions of massive star formation as well as low-density paths through the Galactic halo, allowing us to clearly define the trend of B depletion onto interstellar grains as a function of gas density. Many extended sight lines exhibit complex absorption profiles that trace both local gas and gas associated with either the Sagittarius-Carina or Perseus spiral arm. Our analysis indicates a higher B/O ratio in the inner Sagittarius-Carina spiral arm than in the vicinity of the Sun, which may suggest that B production in the current epoch is dominated by a secondary process. The average gas-phase B abundance in the warm diffuse ISM [log ϵ(B) = 2.38±0.10] is consistent with the abundances determined for a variety of Galactic disk stars, but is depleted by 60% relative to the solar system value. Our survey also reveals sight lines with enhanced B abundances that potentially trace recent production of 11B either by cosmic-ray or neutrino-induced spallation. Such sight lines will be key to discerning the relative importance of the two production routes for 11B synthesis.

Licvd of Cr(C,O) Films from Cr(CO)6 at 248 NM: Gas-Phase and Surface Processes

1988 ◽  
Vol 129 ◽  
Author(s):  
R. Nowak ◽  
L. Konstantinov ◽  
P. Hess
Keyword(s):  
Carbon Monoxide ◽  
Gas Phase ◽  
Laser Fluence ◽  
Film Deposition ◽  
Surface Processes ◽  
Minor Role ◽  
Relative Importance ◽  
Experimental Conditions ◽  
Krf Excimer Laser ◽  
A Minor

ABSTRACTThe influence of laser fluence and carbon monoxide partial pressure on the deposition rate of thin Cr(C,O) films was investigated. The films were deposited from Cr(CO)6 mixtures with CO and Ar using a KrF excimer laser. The observed results are discussed with respect to the relative importance of gasphase and surface processes. The results reveal that under the present experimental conditions chromium atoms produced in the gas phase play only a minor role as direct film precursors in KrF laser-induced film deposition.

Photolysis of SO2 in the Presence of Foreign Gases. VI. Acetylene and Allene

1974 ◽  
Vol 52 (20) ◽  
pp. 3451-3453 ◽  
Author(s):  
Menachem Luria ◽  
Julian Heicklen
Keyword(s):  
Triplet State ◽  
Gas Phase ◽  
Triplet States ◽  
Relative Importance ◽  
Excited Singlet ◽  
Singlet States ◽  
Excited Singlet States ◽  
Allene System

The photolysis of SO2 at 3130 Å and 25 °C in the presence of C2H2 leads to CO, and, in the presence of allene to CO and C2H4 as gas phase products. In the C2H2 system, the CO comes from the two non-emitting triplet states of SO2, 57% from SO2** and 43% from SO2≠. In the allene system, the two excited singlet states of SO2, and possibly the emitting triplet state, also participate. The relative importance of the contributions from each state can be estimated to be >35% from 1SO2, <16% from 3SO2, 8% from SO2*, 12% from SO2**, and 29% from SO2≠.

Gas-phase photolysis of spiropentane at 147.0 nm

1985 ◽  
Vol 63 (12) ◽  
pp. 3593-3596 ◽  
Author(s):  
M. Paller ◽  
R. D. Doepker
Keyword(s):  
Nitric Oxide ◽  
Hydrogen Sulfide ◽  
Gas Phase ◽  
Hydrogen Iodide ◽  
Radical Scavenger ◽  
Relative Importance ◽  
Molecular Processes ◽  
Primary Reaction ◽  
Reaction Channels

The gas-phase photolysis of spiropentane has been investigated using xenon (147.0 nm) resonance radiation. Major products observed in order of decreasing importance are ethylene, aliène, methylacetylene, 1,2-butadiene, acetylene, propylene, and vinylacetylene. Nitric oxide was used as a radical scavenger while hydrogen sulfide and hydrogen iodide were employed as radical interceptors in the determination of the relative importance of radical and molecular processes. CH3/CH2 and CH3C=C• radicals were identified and quantified. Seven primary reaction channels were postulated of which those involving the "elimination" of ethylene were the most predominant accounting for 71% of the photodecomposition.

High-resolution spectroscopy of the (000)–(000) band of the CaOD radical

1994 ◽  
Vol 72 (11-12) ◽  
pp. 1200-1205 ◽  
Author(s):  
Mingguang Li ◽  
John A. Coxon
Keyword(s):  
High Resolution ◽  
Gas Phase ◽  
Ground State ◽  
Measurement Accuracy ◽  
Isotope Effects ◽  
Spin Rotation ◽  
High Resolution Spectroscopy ◽  
Rotational Line ◽  
Measured Line ◽  
Line Positions

The [Formula: see text] (000)–(000) band of the gas-phase CaOD radical has been rotationally analyzed using high-resolution laser spectroscopy. The technique of intermodulated fluorescence was employed to resolve the small spin-rotation splittings in the ground state. The measurement accuracy of the rotational line positions was 0.003 cm−1. The measured line positions have been employed in a least-squares estimation of the molecular constrants for both electronic states. Isotope relations between the constants of CaOH and CaOD are examined, and the constants AD and γ for the Ã2Π(000) level were separated using isotope effects.

scholarly journals Diffuse, Translucent & High-Latitude Clouds: Theoretical Considerations

1992 ◽  
Vol 150 ◽  
pp. 143-151
Author(s):  
E.F. Van Dishoeck
Keyword(s):  
Surface Chemistry ◽  
Gas Phase ◽  
Observational Data ◽  
High Latitude ◽  
Relative Importance ◽  
Grain Surface ◽  
Theoretical Considerations

The relative importance of gas-phase, shock and grain-surface chemistry is discussed with reference to recent observational data. The relation between diffuse, translucent and high-latitude clouds is illustrated with models in which carbon is transformed from atomic (C+, C) to molecular (CO) form with increasing extinction.

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