The Infrared Spectra of Amino Acids and Some Simple Polypeptides to 33 cm−1 at Room and Liquid Nitrogen Temperatures

1971 ◽  
Vol 25 (2) ◽  
pp. 175-182 ◽  
Author(s):  
William R. Feairheller ◽  
J. T. Miller
Keyword(s):  
Amino Acids ◽  
Low Temperature ◽  
Ir Spectra ◽  
Liquid Nitrogen ◽  
Infrared Spectra ◽  
Low Temperatures ◽  
Low Frequency ◽  
Absorption Bands ◽  
Frequency Bands ◽  
Analytical Information

The ir spectra of a number of amino acids have been studied and the absorption bands in the 400–33 cm−1 region are reported. Spectra were recorded at both room and liquid nitrogen temperatures. It was observed that recording at low temperatures is a useful method for obtaining additional analytical information when the amino acids are in the zwitterion form. Low temperature is also useful in determining the assignment of several of the low frequency bands.

scholarly journals MICROSPECTROPHOTOMETRY OF CYTOCHROMES IN THE SINGLE CELL AT ROOM AND LIQUID NITROGEN TEMPERATURES

1965 ◽  
Vol 26 (3) ◽  
pp. 741-746 ◽  
Author(s):  
B. Thorell ◽  
B. Chance ◽  
V. Legallais
Keyword(s):  
Low Temperature ◽  
Single Cell ◽  
Liquid Nitrogen ◽  
Low Temperatures ◽  
Room Temperature ◽  
Single Cells ◽  
Visible Region ◽  
Absorption Bands ◽  
Preliminary Results ◽  
Favorable Conditions

By increasing further the sensitivity of microspectrophotometry, it is now possible to measure, under favorable conditions, the smaller absorption bands of the respiratory pigments of single cells in the visible region of the spectrum. A considerable aid in the distinction between cytochromes is afforded by liquid nitrogen microspectrophotometry. Under favorable conditions, the height of the peaks is increased over 8-fold at low temperatures. In diploid yeast, characteristically sharpened components not resolvable at room temperature are observed at low temperature; and in pentaploid yeast, a hitherto unrecognized pigment is observed at 583 mµ. These preliminary results indicate the feasibility and the value of low temperature microspectrophotometry of biological materials.

Investigation of Spectral Sensitization III. A Study of the Visible and Infrared Spectra of Some Very Pure Bis-Thiazolinyl and Bis-Thiazolyl Cyanine Iodides

1966 ◽  
Vol 20 (3) ◽  
pp. 150-158 ◽  
Author(s):  
A. Leifer ◽  
M. Boedner ◽  
P. Dougherty ◽  
A. Fusco ◽  
M. Koral ◽  
...  
Keyword(s):  
Infrared Spectra ◽  
Low Frequency ◽  
Red Shift ◽  
Absorption Bands ◽  
Spin Resonance ◽  
Visible Spectra ◽  
Bond System ◽  
Phenyl Rings ◽  
In Series ◽  
Systematic Group

A detailed study of the visible spectra in solution and the infrared spectra of the dyes in the solid state have been made for the following vinylogous series of cyanine dyes: [2-bis(3-ethylthiazolinyl)] cyanine iodides, I; [2-bis(3-ethyl-4-methylthiazolyl)] cyanine iodides, II; and [2-bis(3-ethyl-4,5-diphenylthiozolyl] cyanine iodides, III. Each dye, to be acceptable for study, had to be chromatographically pure, give a correct microchemical elemental analysis, and be free of electron-spin resonance (free radical) signals. These vinylogous series of dyes form a systematic group. That is, in series I there is only a resonant conjugated chain of alternate single and double bonds present between the two nitrogen atoms; in series II there are additional olefinic unsaturated bonds which are in conjugation with the resonant conjugated chain; and in series III there are additional phenyl rings in conjugation with the entire pi bond system present in II. The characteristic red shift of the principal absorption maxima was observed for these dyes in the visible as the number of methine linkages increased. Furthermore, a small relative red shift of the absorption maxima has been observed for this group of dyes and has been interpreted on the basis of the type of unsaturation present in conjugation with the resonant conjugated chain. Assignments of vibrational modes to separate absorption regions have been made for these vinylogous series of dyes. A correlation of the dye structure with the absorption bands has been made. Each vinylog gave rise to a characteristic pattern of resonant conjugated stretching modes in the region 1600 to 1400 cm−1. These modes exhibited a low frequency shift as the resonant conjugated chain-length increased. For a constant number of polymethine linkages these modes are a function of the type of unsaturation present which is in conjugation with the resonant conjugated chain.

A Low Temperature Infrared Study of Self-association in Thiols

1972 ◽  
Vol 50 (22) ◽  
pp. 3594-3600 ◽  
Author(s):  
R. Bicca de Alencastro ◽  
C. Sandorfy
Keyword(s):  
Hydrogen Bonding ◽  
Low Temperature ◽  
Infrared Spectra ◽  
Low Temperatures ◽  
Infrared Study ◽  
Text Type ◽  
Stretching Vibration ◽  
Aliphatic Thiols ◽  
Self Association ◽  
Associated Species

The infrared spectra of several aliphatic thiols and of benzenethiol were measured between 2400 and 2700 cm−1, and 4800 and 5300 cm−1 in a 1:1 mixture of CCl3F and C2F4Br2, at temperatures ranging from 20 to −190 °C. Dimerization takes place at low temperatures and more highly associated species also appear. Free S—H groups are present in the solutions as well as in the pure liquids, even at the lowest temperatures. The association is of the [Formula: see text] type in aliphatic thiols; both [Formula: see text] and [Formula: see text] bonds are found in the case of benzenethiol and α-toluenethiol. Hydrogen bonding has little effect on the anharmonicity of the S—H stretching vibration.

Thermoelectric Module For Low Temperature Applications

2001 ◽  
Vol 691 ◽  
Author(s):  
Sangeeta Lal ◽  
Sim Loo ◽  
Duck-Young Chung ◽  
Theodora Kyratsi ◽  
Mercouri G. Kanatzidis ◽  
...  
Keyword(s):  
Low Temperature ◽  
Liquid Nitrogen ◽  
Low Temperatures ◽  
High Performance ◽  
Figure Of Merit ◽  
Thermoelectric Module ◽  
Thermoelectric Cooling ◽  
Cooling Device ◽  
Transport Measurements ◽  
Theoretical Simulations

ABSTRACTThe possibility of a prototype thermoelectric cooling device for operation near liquid nitrogen temperatures has been explored. In these devices, the figure of merit involves a combination of the properties of the two branches of the module. Here, we investigate the fabrication of a module with a new low temperature material, CsBi4Te6 (p-type), and the best known low temperature n-type materials Bi85Sb15. Transport measurements for each of these materials show high performance at low temperatures. Known values for the figure of merit Zmax of CsBi4Te6 is 3.5 × 10−3 K−1 at 225K and for Bi85Sb15 is 6.5 × 10−3 K−1 at 77K. At 100K these values drop to 2.0×10−3 K−1 for CsBi4Te6 and 6.0×10−3 K−1 for Bi85Sb15. Theoretical simulations based on these data show a cooling of δT = 12K at 100K, which is almost three times the efficiency of a Bi2Te3 module at that temperature. We present transport measurements of elements used in the fabrication of a low temperature thermoelectric module and properties of the resulting module.

Infrared Spectra of Amino Acids in the 700-400 cm−1 Region

1966 ◽  
Vol 49 (5) ◽  
pp. 1083-1085
Author(s):  
R J Warren ◽  
W E Thompson ◽  
J E Zarembo ◽  
I B Eisdorfer
Keyword(s):  
Amino Acids ◽  
Spectral Data ◽  
Infrared Spectra ◽  
Absorption Bands ◽  
Structure Correlations ◽  
Infrared Data

Abstract The spectra of 49 amino acids and closely related metabolites of varying structure have been studied and analyzed in the region 700–400 cm−1; these amino acids have four characteristic bands in this region. Spectra-structure correlations and assignments of the absorption bands are presented and discussed. This compilation of data is an important supplement to existing infrared data in the 4000–650 cm−1 range. It should provide spectral data for ready identification of a large number of amino acids and make it possible to verify spectral data which is either inconclusive or ambiguous.

An Infrared Study of Metal Isopropoxide Precursors for SrTiO3

1984 ◽  
Vol 32 ◽  
Author(s):  
R. E. Riman ◽  
D. M. Haaland ◽  
C.J.M. Northrup ◽  
H. K. Bowen ◽  
A. Bleier
Keyword(s):  
Ir Spectra ◽  
Detailed Analysis ◽  
Infrared Spectra ◽  
Spectral Features ◽  
Absorption Bands ◽  
Infrared Study ◽  
Characteristic Absorption ◽  
Local Environments ◽  
Insight Into ◽  
Hydrolysis Reactions

ABSTRACTA Sr/Ti bimetallic isopropoxide complex was synthesized by two methods. The complex served as a precursor to the production of homogeneous SrTiO3 powders via alkoxide hydrolysis. Infrared spectra were obtained for Sr(OPri)2, Ti(OPri)4, and the product of the syntheses. In addition, the IR spectra of the solutions of each of the alkoxides were followed as hydrolysis reactions proceeded. Detailed analysis of the spectral features support the existence of a 1:1 Sr/Ti bimetallic alkoxide. The new Sr/Ti compound exhibits characteristic absorption bands at (1017, 993, 972, 961 cm−1), (844, 838, 827 cm−1) and (620, 596, and 572 −1). A band at 819−1 might also be associated with the new Sr/Ti bimetallic alkoxide. The infrared spectra suggest that the isopropoxide ligands in the bimetallic alkoxide are in at least three separate local environments. This information offers insight into possible structures for the complex.

scholarly journals Low-temperature infrared study of ammonium carbamate formation

1984 ◽  
Vol 62 (5) ◽  
pp. 945-948 ◽  
Author(s):  
C. Hisatsune
Keyword(s):  
Solid State ◽  
Low Temperature ◽  
Infrared Spectra ◽  
Low Temperatures ◽  
Hydrogen Ion ◽  
Ion Transfer ◽  
Infrared Study ◽  
Ammonium Carbamate

Two types of infrared spectra observed during the formation of ammonium carbamate [Formula: see text] from the reaction of NH3 and CO2 in the solid state at low temperatures have been re-examined. These spectra had been assigned previously to amorphous and crystalline ammonium carbamate but the present data suggest their origins to be [Formula: see text] and its unstable precursor (NH3)2CO2 in which CO2 is bent. Spectra of amorphous and crystalline ammonium carbamate have been distinguished by comparing the systems NH3/CO2 and NH3/CO2/H2O. Hydrogen ion transfer in the diammoniates occurred at about −80 °C for NH3/CO2 and about −40 °C for ND3/CO2.

scholarly journals CRYOGENIC AIR CONDITIONING OF MOTOR VEHICLES

2014 ◽  
pp. 100-103
Author(s):  
M. JAIVIGNESH ◽  
DR. B. VIJAYA RAMNATH
Keyword(s):  
Low Temperature ◽  
Liquid Helium ◽  
Liquid Nitrogen ◽  
Low Temperatures ◽  
Air Conditioning ◽  
Absolute Zero ◽  
Motor Vehicles ◽  
Air Conditioning System ◽  
Low Temperature Refrigeration ◽  
Physical Phenomena

Cryogenics is the branch of physics and engineering that involves the study of very low temperatures (below 123 K), how to produce them, and how materials behave at those temperatures. It is frequently applied to low temperature refrigeration applications such as in the study of physical phenomena of materials at temperature approaching absolute zero and in the liquefaction of gases. Liquefied gases such as liquid nitrogen and liquid helium are used in many cryogenic applications. Using liquid nitrogen as a refrigerant reduces chloro-fluorocarbon (CFC) emission in atmosphere and it is an eco-friendly technique. This paper deals with usage of liquid nitrogen in air conditioning of motor vehicles. First the preparation of liquid nitrogen is discussed, followed by its storage and working as a refrigerant in air conditioning system. This is followed by its advantages and draw backs.

Examinations of the Matrix Isolation Fourier Transform Infrared Spectra of Organic Compounds: Part XVI

1989 ◽  
Vol 43 (6) ◽  
pp. 1008-1016 ◽  
Author(s):  
W. M. Coleman ◽  
Bert M. Gordon
Keyword(s):  
Fourier Transform ◽  
Ir Spectra ◽  
Vapor Phase ◽  
Infrared Spectra ◽  
Condensed Phase ◽  
Matrix Isolation ◽  
Absorption Bands ◽  
Argon Matrix ◽  
The Matrix ◽  
The Impact

Information concerning the matrix isolation Fourier transform infrared spectra of a series of alkanes, esters, lactones, lactams, phenols, alcohols, amides, alkenes, and ketones is presented. A comparison between the characteristics of the spectra in two matrices (argon and xenon) as well as in the absence of any matrix (bare gold disk) is drawn. The impact of these matrices on the characteristics of the IR spectra is compared with the impact observed when spectra are gathered in the vapor phase as well as the condensed phase/solid state. For the majority of compounds studied, the major absorption bands of each class of compound fall between higher values for the vapor phase and lower values for the condensed phase when either argon or xenon is used as the matrix gas. The few exceptions are discussed. The absorption bands found in the xenon matrix are usually at a lower energy than are comparable bands in the argon matrix. In most all cases, the values of absorptions for compounds on the bare disk were lower than the comparable values found in the argon matrix. These results represent the first extensive study at 10 K of the effect of different matrix gas hosts and document the proposal that preconceptions of noble gases as inert hosts for the examination of FT-IR spectra at low temperature are not valid.

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