High sensitivity photoacoustic spectrometer for variable temperature solution studies

1990 ◽  
Vol 61 (5) ◽  
pp. 1395-1403 ◽  
Author(s):  
James V. Beitz ◽  
M. M. Doxtader ◽  
V. A. Maroni ◽  
S. Okajima ◽  
D. T. Reed
Keyword(s):  
Variable Temperature ◽  
High Sensitivity ◽  
Photoacoustic Spectrometer ◽  
Solution Studies ◽  
Temperature Solution

scholarly journals 3D Unsteady Diffusion and Reaction-Diffusion with Singularities by GFEM with 27-Node Hexahedrons

2014 ◽  
Vol 2014 ◽  
pp. 1-12 ◽  
Author(s):  
Estaner Claro Romão
Keyword(s):  
Finite Element ◽  
Variable Temperature ◽  
Three Dimensional ◽  
Reaction Diffusion ◽  
Third Order ◽  
Order Of Accuracy ◽  
Finite Element Approximations ◽  
Temperature Solution ◽  
The One ◽  
Primary Variable

The Galerkin Finite Element Method (GFEM) with 8- and 27-node hexahedrons elements is used for solving diffusion and transient three-dimensional reaction-diffusion with singularities. Besides analyzing the results from the primary variable (temperature), the finite element approximations were used to find the derivative of the temperature in all three directions. This technique does not provide an order of accuracy compatible with the one found in the temperature solution; thereto, a calculation from the third order finite differences is proposed here, which provide the best results, as demonstrated by the first two applications proposed in this paper. Lastly, the presentation and the discussion of a real application with two cases of boundary conditions with singularities are proposed.

Solution Studies of the Dynamic Stereochemistry of Palladium(II) Carboxylate Complexes

1975 ◽  
Vol 53 (17) ◽  
pp. 2558-2574 ◽  
Author(s):  
Thomas R. Jack ◽  
John Powell
Keyword(s):  
Ring Opening ◽  
Variable Temperature ◽  
Equilibrium Constants ◽  
Quantitative Measure ◽  
Intermediate Species ◽  
Tertiary Phosphine ◽  
Crystalline Complex ◽  
Carboxylate Complexes ◽  
Solution Studies ◽  
Dynamic Stereochemistry

A series of dimeric tertiary phosphine carboxylate complexes of palladium(II) of the general types [(PR3)Pd(O2CR)2]2 and [(PR3)Pd(O2CR)(O2CR)]2 have been synthesized and struc-turally characterized. The dynamic stereochemistry of the complexes where PR3 = Me2PhP has been investigated using variable temperature n.m.r. techniques. Exchange of the stereochemically nonequivalent methyl groups of the coordinated Me2PhP ligand occurs via a solvent assisted process involving ring opening of the "Pd2(OCO)2" bridged structure. For the trifluoroacetate complexes solution equilibria between monomer and dimer are readily apparent at low temperatures in the 19F n.m.r. The observed equilibrium constants are a function of the solvent and the size of the PR3 ligand. The reaction of [(PMe2Ph)Pd(O2CCF3)2]2 with excess AgO2CCF3 gives an unusual crystalline complex of stoichiometry Ag[(PMe2Ph)Pd(O2CCF3)3]. A quantitative measure of the ability of a coordinated carboxylate to stabilize intermediate species via chelation has been obtained from a variable temperature n.m.r. study of [(Π-2-methylallyl)Pd(O2CR)(Me2PhP)] (R=CH3, CH2Cl, CHCl2, CCl3, CF3, CMe3, CPh3, CH2Ph).

A carbon-13 CP/MAS nuclear magnetic resonance study of several 1,4-disubstituted benzenes in the solid state

1989 ◽  
Vol 67 (3) ◽  
pp. 525-534 ◽  
Author(s):  
Glenn H. Penner ◽  
Roderick E. Wasylishen
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Solid State ◽  
Magnetic Resonance ◽  
Chemical Shifts ◽  
Substituent Effects ◽  
Nuclear Magnetic Resonance Study ◽  
Solution Studies ◽  
Temperature Solution ◽  
Cp Mas Nmr ◽  
Nuclear Magnetic

The carbon-13 chemical shifts of several 1,4-disubstituted benzenes in the solid state are reported. At least one of the substituents is unsymmetrical and in most cases this leads to different 13C chemical shifts of C-2 and C-6 and in some cases to different shifts for C-3 and C-5. The 13C chemical shifts observed in the solid state are compared with those measured in solution and, where possible, with those obtained in low temperature solution studies where internal rotation of the unsymmetrical substituent is slow on the 13C chemical shift time scale. Agreement between the chemical shifts observed in the solid state and solution is excellent. The potential application of CP/MAS nuclear magnetic resonance in deducing the conformation of benzene derivatives with two unsymmetrical substituents is discussed. Keywords: carbon-13 CP/MAS NMR, 13C NMR chemical shifts, substituent effects.

scholarly journals High sensitivity variable-temperature infrared nanoscopy of conducting oxide interfaces

2019 ◽  
Vol 10 (1) ◽  
Author(s):  
Weiwei Luo ◽  
Margherita Boselli ◽  
Jean-Marie Poumirol ◽  
Ivan Ardizzone ◽  
Jérémie Teyssier ◽  
...  
Keyword(s):  
Variable Temperature ◽  
High Sensitivity ◽  
Oxide Interfaces

scholarly journals P3HT:PCBM blend films phase diagram on the base of variable-temperature spectroscopic ellipsometry

2018 ◽  
Vol 9 ◽  
pp. 1108-1115 ◽  
Author(s):  
Barbara Hajduk ◽  
Henryk Bednarski ◽  
Bożena Jarząbek ◽  
Henryk Janeczek ◽  
Paweł Nitschke
Keyword(s):  
Phase Transitions ◽  
Spectroscopic Ellipsometry ◽  
Variable Temperature ◽  
Acid Methyl Ester ◽  
High Sensitivity ◽  
Transition Temperatures ◽  
Blend Films ◽  
Phase Transition Temperatures ◽  
Depth Study ◽  
Good Guess

In this work we present an in-depth study of the how the composition of poly(3-hexylthiophene) (P3HT):[6,6]-phenyl-C61-butyric acid methyl ester (PCBM) blend films influences their phase transitions using variable-temperature spectroscopic ellipsometry. We demonstrate that this non-destructive method is a very sensitive optical technique to investigate the phase transitions and to determine the glass transition temperatures and melting crystallization points of the P3HT:PCBM blend films. By analyzing the influence of the temperature T on the raw ellipsometric data, we have identified a high sensitivity of the ellipsometric angle Δ at a wavelength of 280 nm to temperature changes. Characteristic temperatures determined from the slope changes of the Δ(T) plot appeared to be very good guess values for the phase transition temperatures.

A Low-Temperature High-Sensitivity Field-Cycling Spectrometer for Quadrupole Double Resonance Spectroscopy

1990 ◽  
Vol 45 (3-4) ◽  
pp. 595-598 ◽  
Author(s):  
M. M. P. Khurshid ◽  
F. Zhenye ◽  
J.A.S. Smith
Keyword(s):  
Variable Temperature ◽  
Double Resonance ◽  
High Sensitivity ◽  
Resonance Spectroscopy ◽  
Quadrupole Resonance ◽  
Field Cycling ◽  
Double Resonance Spectroscopy ◽  
Nuclear Quadrupole ◽  
The Magnetic Field ◽  
Sensitivity Field

Abstract This paper discusses the design of a variable-temperature high-sensitivity field cycling spectrometer for nuclear magnetic resonance and nuclear quadrupole double resonance experiments. The instrument is capable of detecting N-14 quadrupole resonance signals from samples as small as 0.1 g down to temperatures of 150 K. The magnetic field cycling is performed by mechanical transfer of the sample using a pair of switchable electromagnetic solenoids, in times of about 0.2 s.

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