An Interpretation of the Infrared Spectrum of Carbon Monoxide in a Solid Xenon Matrix

1971 ◽  
Vol 49 (15) ◽  
pp. 2018-2027 ◽  
Author(s):  
K. O. Lee
Keyword(s):  
Carbon Monoxide ◽  
Large Fraction ◽  
Infrared Band ◽  
Band Shape ◽  
Hindered Rotation ◽  
Gaseous Molecule ◽  
Carbon Monoxide Molecule ◽  
The Matrix ◽  
Librational Motion ◽  
Broad Feature

The infrared absorption band centered at 2133.1 cm−1 of carbon monoxide isolated in solid xenon at 20 °K has been interpreted as due to hindered rotation of the carbon monoxide molecule. The intermolecular interaction, comprising contributions mainly due to dispersion and repulsion, between carbon monoxide and the matrix produces an orientational effect. The rotational motion of the carbon monoxide molecule in the intermolecular field is treated quantum-mechanically so as to account for the main spectral features observed experimentally. From the calculations it is shown that a fraction of CO molecules in the matrix may undergo nearly free rotation to give a broad feature in the infrared band shape resembling the P- and R-branch envelope of the gaseous molecule in the wings. A large fraction of the CO molecules, those with energies less than the potential barrier height, execute librational motion, and thus are responsible for the intense Q branch at the band center.In a smaller matrix cavity, e.g., carbon monoxide in an argon or a krypton crystal, the "over-distortion" of the site would inhibit rotation altogether.

Infrared Band-Shape Studies of Sulphate Glasses

1982 ◽  
Vol 37 (2) ◽  
pp. 191-195
Author(s):  
H. G. K. Sundar ◽  
R. Parthasarathy ◽  
K. J. Rao
Keyword(s):  
Glass Transition ◽  
Transition Temperature ◽  
Glass Transition Temperature ◽  
Shape Analysis ◽  
Cluster Model ◽  
Deformation Band ◽  
Infrared Band ◽  
Band Shape ◽  
Correlation Times ◽  
Second Moments

Abstract IR band-shape analysis has been carried out on the 620 cm-1 deformation band of the sulphate ion in several Na2SO4-K2SO4-ZnSO4 glasses. Variations of correlation times and second moments suggest that reorientational motions of sulphate ions begin to evolve prior to the glass-transition temperature. The correlation times may support a cluster model for the glass-transition.

Lasers on overtone transitions of carbon monoxide molecule

Laser Physics ◽  
2010 ◽  
Vol 20 (1) ◽  
pp. 144-186 ◽  
Author(s):  
A. A. Ionin ◽  
A. K. Kurnosov ◽  
A. P. Napartovich ◽  
L. V. Seleznev
Keyword(s):  
Carbon Monoxide ◽  
Carbon Monoxide Molecule

scholarly journals Do nitric oxide, carbon monoxide and hydrogen sulfide really qualify as ‘gasotransmitters’ in bacteria?

2018 ◽  
Vol 46 (5) ◽  
pp. 1107-1118 ◽  
Author(s):  
Lauren K. Wareham ◽  
Hannah M. Southam ◽  
Robert K. Poole
Keyword(s):  
Nitric Oxide ◽  
Carbon Monoxide ◽  
Hydrogen Sulfide ◽  
Small Molecule ◽  
Toxic Effects ◽  
Gaseous Molecule ◽  
Recent Advances ◽  
Definition Of

A gasotransmitter is defined as a small, generally reactive, gaseous molecule that, in solution, is generated endogenously in an organism and exerts important signalling roles. It is noteworthy that these molecules are also toxic and antimicrobial. We ask: is this definition of a gasotransmitter appropriate in the cases of nitric oxide, carbon monoxide and hydrogen sulfide (H2S) in microbes? Recent advances show that, not only do bacteria synthesise each of these gases, but the molecules also have important signalling or messenger roles in addition to their toxic effects. However, strict application of the criteria proposed for a gasotransmitter leads us to conclude that the term ‘small molecule signalling agent’, as proposed by Fukuto and others, is preferable terminology.

Employing X-ray scattering to characterize materials with grain sizes in the nano-regime

2008 ◽  
Vol 23 (2) ◽  
pp. 96-100 ◽  
Author(s):  
E. A. Laitila ◽  
D. E. Mikkola
Keyword(s):  
Crystallite Size ◽  
Large Fraction ◽  
Matrix Material ◽  
Background Intensity ◽  
X Ray ◽  
Volume Fractions ◽  
X Ray Scattering ◽  
The Matrix ◽  
Diffraction Peaks ◽  
Ray Scattering

This study focuses on characterization of an (Al,Cr)3Ti alloy processed together with titanium powder by reactive mechanical milling (RMM) to produce an ultrafine grained intermetallic alloy matrix with in situ carbide and hydride phases formed during processing. Observations of X-ray scattering as RMM processing time increases show severe broadening of matrix diffraction peaks, accompanied by the appearance of diffraction peaks resulting from the formation of very small crystallites of TiC and TiH1.92 phases with increasing volume fractions, and finally, increasing background intensity as the crystallite size of the matrix phase decreases to ∼2 nm. Estimates of phase volume fractions were made by the direct comparison method, along with crystallite sizes by Warren–Averbach peak profile analysis. The general increase in background intensities has been attributed to random static displacements of the large fraction of atoms located within the grain boundary regions. Further, it has been concluded that the matrix material with a crystallite size of a few nanometers has about half the atoms in statically displaced positions defining the boundary regions. The results argue that background intensity changes should not be ignored and are useful in interpreting scattering from these nano-scale materials.

scholarly journals Complementary roles of gasotransmitters CO and H2S in sleep apnea

2017 ◽  
Vol 114 (6) ◽  
pp. 1413-1418 ◽  
Author(s):  
Ying-Jie Peng ◽  
Xiuli Zhang ◽  
Anna Gridina ◽  
Irina Chupikova ◽  
David L. McCormick ◽  
...  
Keyword(s):  
Carbon Monoxide ◽  
Sleep Apnea ◽  
The United States ◽  
Major Health Problem ◽  
Major Health ◽  
Spontaneously Hypertensive ◽  
Effector Molecule ◽  
Genetic Ablation ◽  
Gaseous Molecule ◽  
Pharmacologic Inhibition

Sleep apnea, which is the periodic cessation of breathing during sleep, is a major health problem affecting over 10 million people in the United States and is associated with several sequelae, including hypertension and stroke. Clinical studies suggest that abnormal carotid body (CB) activity may be a driver of sleep apnea. Because gaseous molecules are important determinants of CB activity, aberrations in their signaling could lead to sleep apnea. Here, we report that mice deficient in heme oxygenase-2 (HO-2), which generates the gaseous molecule carbon monoxide (CO), exhibit sleep apnea characterized by high apnea and hypopnea indices during rapid eye movement (REM) sleep. Similar high apnea and hypopnea indices were also noted in prehypertensive spontaneously hypertensive (SH) rats, which are known to exhibit CB hyperactivity. We identified the gaseous molecule hydrogen sulfide (H2S) as the major effector molecule driving apneas. Genetic ablation of the H2S-synthesizing enzyme cystathionine-γ-lyase (CSE) normalized breathing inHO-2−/−mice. Pharmacologic inhibition of CSE withl-propargyl glycine prevented apneas in bothHO-2−/−mice and SH rats. These observations demonstrate that dysregulated CO and H2S signaling in the CB leads to apneas and suggest that CSE inhibition may be a useful therapeutic intervention for preventing CB-driven sleep apnea.

A COMPARISON OF OPTIMIZATION METHODS FOR FITTING CURVES TO INFRARED BAND ENVELOPES

1966 ◽  
Vol 44 (24) ◽  
pp. 3031-3050 ◽  
Author(s):  
J. Pitha ◽  
R. Norman Jones
Keyword(s):  
Least Squares ◽  
Computation Time ◽  
Direct Methods ◽  
Nonlinear Least Squares ◽  
Optimization Methods ◽  
Infrared Band ◽  
Band Shape ◽  
Analytical Functions ◽  
Degree Of Convergence ◽  
Better Than

A comparison has been made of seven numerical methods of fitting infrared absorption band envelopes with analytical functions using nonlinear least squares approximations. Gauss and Cauchy (Lorentz) band shape functions are used, and also sum and product combinations of the two. The methods have been compared with respect to both the degree of convergence and to the computation time needed to achieve an acceptable fit.The most effective method has matched the overlap envelope of a steroid spectrum containing 16 bands; this necessitated the optimization of 65 variables. More complex spectra can be dealt with by a "moving subspace" modification in which only the parameters of a group of adjacent bands are adjusted at one time. Automatic computer programs have been written for five of the methods, and for the moving subspace modification. These will be published elsewhere.If the computed curve is convoluted with the spectral slit function before making the least squares calculations, the distortion of the observed spectrum caused by the finite spectral slit width can be corrected. In some cases this method of diminishing the slit distortion is better than direct methods, particularly when dealing with strongly overlapped bands.

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