81Br and 127 I NQR Studies of (CH3NH3)2HgBr4 and (CH3NH3)2HgI4

1992 ◽  
Vol 47 (1-2) ◽  
pp. 99-105
Author(s):  
Hiromitsu Terao ◽  
Tsutomu Okuda ◽  
Aya Minami ◽  
Takashi Matsumoto ◽  
Yoshio Takeda
Keyword(s):  
Temperature Dependence ◽  
Room Temperature ◽  
Isotope Effects ◽  
Molecular Motions ◽  
Resonance Frequencies ◽  
Wide Range ◽  
Large Asymmetry ◽  
Increasing Temperature ◽  
Asymmetry Parameters ◽  
Positive Frequency

AbstractThe 81Br and 127I NQR frequencies in (CH3NH3 ) 2HgBr4 and (CH3NH3 ) 2HgI4 , respectively, have been recorded from above 77 K to around room temperature. The resonance lines exist in a wide range of frequencies. An unusual temperature dependence of the resonance frequencies has been observed. Small 1H - 2D isotope effects have been observed between (CH3ND3 )2HgBr4 and (CH3NH3 ) 2HgBr4 . Both negative and positive frequency differences between the deuterated and the nondeuterated compound have been observed at 77 K. The relatively large asymmetry parameters in the iodine compound decrease with increasing temperature, indicating the existence of H-bonds. The present results are interpreted qualitatively by considering the effects of H-bonding, N - H • • • X, between the halogen atoms and the CH3NH3 ions which may undergo large molecular motions. It is suggested that not only frequency-lowering but also frequency-rising effects may be produced, depending on the direction of the H-bond, i.e., the angle between the Hg -X bond and the X • • • H bond.

Dielectric Properties of Pulsed Excimer Laser Ablated BaBi2Nb2O9 Thin Films

2002 ◽  
Vol 748 ◽  
Author(s):  
Apurba Laha ◽  
S. B. Krupanidhi ◽  
S. Saha
Keyword(s):  
Thin Films ◽  
Phase Transition ◽  
Dielectric Constant ◽  
Temperature Dependence ◽  
Loss Tangent ◽  
Dielectric Response ◽  
Room Temperature ◽  
Dielectric Constant And Loss ◽  
Wide Range ◽  
Room Temperature Dielectric Constant

ABSTRACTThe dielectric response of BaBi2Nb2O9 (BBN) thin films has been studied as a function of frequency over a wide range of temperatures. Both dielectric constant and loss tangent of BBN thin films showed a ‘power law’ dependence with frequency, which was analyzed using the Jonscher's universal dielectric response model. Theoretical fits were utilized to compare the experimental results and also to estimate the value of temperature dependence parameters such as n(T) and a(T) used in the Jonscher's model. The room temperature dielectric constant (ε') of the BBN thin films was 214 with a loss tangent (tanδ) of 0.04 at a frequency of 100 kHz. The films exhibited the second order dielectric phase transition from ferroelectric to paraelectric state at a temperature of 220 °C. The nature of phase transition was confirmed from the temperature dependence of dielectric constant and sponteneous polarization,respectively. The calculated Currie constant for BBN thin films was 4 × 105°C.

Internal Cation Mobilities and Their Isotope Effects in the Molten System (Li, K)NO3

1987 ◽  
Vol 42 (7) ◽  
pp. 683-689 ◽  
Author(s):  
Arnold Lundén ◽  
Junko Habasaki ◽  
Isao Okada
Keyword(s):  
Binary System ◽  
Eutectic Composition ◽  
Isotope Effects ◽  
Wide Range ◽  
Internal Mobility ◽  
Space Effect ◽  
High Concentrations ◽  
Increasing Temperature ◽  
Crossing Point ◽  
Very High

With the Klemm method internal mobility ratios of the two cations have been measured for melts of the binary system (Li, K ) NO3 over a wide range of temperature and composition, and their isotope effects have been determined near the eutectic composition. The Chemla effect has been observed. With increasing temperature the Chemla crossing point shifts, as expected, toward higher concentrations of the smaller cation. At very high concentrations of LiNO3 the mobility of K+ tends to decrease, which is attributed to the free space effect. For both Li+ and K+ the isotope effect increases with temperature.

Temperature Dependence of 2H Quadrupole Coupling Constants in 2H2O and Ionic Motions in Crystalline [M(2H2O)6] [SnCl6] (M: Mg, Ca), Studied by 2H NMR and Neutron Powder Diffraction

1998 ◽  
Vol 53 (6-7) ◽  
pp. 473-479 ◽  
Author(s):  
Naohiro Yoshida ◽  
Noriko Onoda-Yamamuro ◽  
Shin'ichi Ishimaru ◽  
Keizo Horiuchi ◽  
Ryuichi Ikeda
Keyword(s):  
Temperature Dependence ◽  
Powder Diffraction ◽  
Room Temperature ◽  
Neutron Powder Diffraction ◽  
Coupling Constants ◽  
H Nmr ◽  
Octahedral Cation ◽  
Quadrupole Coupling ◽  
Large Asymmetry ◽  
Motional Narrowing

Abstract The temperature dependence of 2H NMR spectra was measured at 130-430 K on [M(D2O)6] [SnCl6] (M : Mg, Ca) (rhombohedral, space group: R3̅), and neutron powder diffraction on the Mg salt was performed at room temperature. Based on the accurate orientation of D2O molecules in an octahedral cation, spectra with a large asymmetry parameter η, observed around 200 K, were explained by a model of 180° flip of water molecules. Another motional narrowing observed above room temperature was assigned to a cationic overall reorientation about the C3-axis.

Article

1999 ◽  
Vol 77 (5-6) ◽  
pp. 733-737
Author(s):  
Maurice M Kreevoy ◽  
Victor G Young, Jr.
Keyword(s):  
Isotope Effect ◽  
Dihedral Angle ◽  
Room Temperature ◽  
Isotope Effects ◽  
Water Molecules ◽  
Aromatic Rings ◽  
Structural Water ◽  
The Mean ◽  
Increasing Temperature ◽  
Ubbelohde Effect

The crystal structure of sodium hydrogen bis(4-nitrophenoxide) dihydrate, 1, with deuterium replacing hydrogen in the bridge and the structural water molecules, has been determined crystallographically at 113, 173, and 295 K. The structure of 1 had previously been determined at similar temperatures (Kreevoy et al.). The O,O distances are 1.5-1.7 pm greater in the deuterated compound than in the undeuterated, at all three temperatures, providing another example of an Ubbelohde effect in a Speakman-Hadzi compound. The temperature invariance of the Ubbelohde effect at temperatures up to room temperature is evidence against centralization of the hydron within this temperature range. It has previously been suggested (Kreevoy et al.) that simplification of the IR spectrum of 1 with increasing temperature is due to an increase in the rate of the hydron shift between the two basic oxygens. This suggestion is strengthened by the elimination of hydron centralization as an alternative. The O,O distance in 1 also increases with temperature, and the dihedral angle between the mean planes of the two aromatic rings decreases. Similarly, the increase in the O,O distance with isotopic substitution is accompanied by a small decrease in the dihedral angle; another geometric isotope effect. Ubbelohde effects in Speakman-Hadzi compounds make the geometric isotope effects found computationally in the critical complexes for hydron, hydrogen atom, or hydride transfer more credible.Key words: low-barrier hydrogen bond, Speakman-Hadzi compound, geometric isotope effect, Ubbelohde effect.

Room-Temperature Nanoimprint Lithography

2006 ◽  
Vol 961 ◽  
Author(s):  
Ken-Ichiro Matsui ◽  
Shinji Matsui
Keyword(s):  
Liquid Phase ◽  
Temperature Dependence ◽  
Nanoimprint Lithography ◽  
Room Temperature ◽  
Hydrogen Silsesquioxane ◽  
Wide Range ◽  
One Step

ABSTRACTRoom-temperature nanoimprint lithography (RT-NIL) using spin-coated hydrogen silsesquioxane (HSQ) resin as the replication material was developed. HSQ pattern with 50 nm linewidth was successfully obtained by the RT-NIL. Postbaking temperature dependence of a HSQ imprinted depth on a mold linewidth was investigated. HSQ imprinted depth had a dependence on the mold linewidth. This revealed that the RT-NIL is suitable for the linewidths of below 1 mm. Furthermore, we have also developed a new imprinting technique that uses liquid-phase hydrogen silsesquioxane (HSQ) as an alternative to the spin-coated HSQ resin. The liquid-phase HSQ imprint technique enabled fabrication of various HSQ patterns with a wide range of linewidths from 25 nm to 300 mm. Arbitrary patterns, including both submicron and greater than 100 micron patterns, were simultaneously replicated with a one-step imprint process, something very difficult to accomplish with spin-coated HSQ. Moreover, after imprinting, the residual HSQ layer in the compressed area was less than 10 nm thick.

Variability and temperature dependence of the velocity of retrograde particle transport in myelinated axons

1981 ◽  
Vol 59 (8) ◽  
pp. 857-863 ◽  
Author(s):  
Richard S. Smith ◽  
Paul D. Cooper
Keyword(s):  
Temperature Dependence ◽  
Particle Velocity ◽  
Coefficient Of Variation ◽  
Room Temperature ◽  
Common Mechanism ◽  
Morphological Evidence ◽  
Myelinated Axons ◽  
Wide Range ◽  
Significant Difference ◽  
The Mean

The velocity of the retrograde transport of optically detectable particles was studied in isolated myelinated axons from Xenopus laevis at room temperature and with varying temperature. At room temperature (22–23.1 °C) the mean particle velocity was significantly different in some axons of the same animal. Results pooled from a number of axons did not indicate any significant difference in the average particle velocity in different animals. At room temperature, even though the mean particle velocity might differ between axons, the coefficient of variation of particle velocity in separate fibers tended to remain constant.The temperature dependence of mean particle velocity (V) could be adequately described by the relationship V = 0.26 exp 0.073T – 0.33, where V is in micrometres per second and T is degrees Celsius. Throughout the temperature range at which transport took place (approximately 5–35 °C) the coefficient of variation of particle velocity remained approximately constant at 0.40. All particles ceased their motion abruptly, and to some extent reversibly, at 37 °C. On morphological evidence, none of the effects of temperature appeared to be related to microtubule depolymerization.The results indicate that retrogradely transported particles with a wide range of velocities respond homogeneously to temperature changes. This supports the view that a common mechanism may underlie the motion of all the particles. No evidence was obtained that the differences between axons at room temperature could be attributed to the presence in separate axons of dissimilar proportions of faster and slower particles. Nor was the velocity–temperature characteristic in the region of room temperature sufficiently steep to explain the differences between axons. It is suggested that axons may differ in general mechanical or chemical properties so that the motion of all particles is affected uniformly.

Moisture Detection Method in Ceramic Package by Slight Current Measurement

1997 ◽  
Author(s):  
A. Hirai ◽  
T. Kikuchi ◽  
H. Namba ◽  
J. Sato
Keyword(s):  
Temperature Dependence ◽  
Leakage Current ◽  
Room Temperature ◽  
Standard Sample ◽  
Detection Method ◽  
Current Measurement ◽  
Fine Ceramic ◽  
Moisture Detection ◽  
Increasing Temperature

Abstract A method of measuring moisture in the ceramic Package (pKG) without the destruction of the samples was developed (We define KNH method: kinahi method). The moisture oondition in the cavity can be oonfirmed by the temperature dependence of the leakage current between adjaoont terminals (At least one of measured terminals is non-oonnect). This method is performed by measuring the leakage current between non-oonnect terminals at various temperatures. The temperature is raised from room temperature. In the caseof the standard sample which has no moisture in the cavity, the leakage current increases as the temperature is raised. However, a sample which has a large amount of moisture in the cavity has a leakage current that decreases with increasing temperature and increases after this cycle. When the temperature is raised, the leakage current decreases because of a decrease in oondensed moisture. After the temperature without oondensing, the leakage current increases as same as standard sample. When this KNH method is used for the product which has no non-oonnect terminals, the leakage current can be measured by using the signal terminals at 0.2V which is the voltage under Vt of protection diode. This KNH method is very useful for oonfirmation of the slight leakage current of fine ceramic PKG and for the amount of moisture in the cavity

scholarly journals Temperature and acid concentration in the search for optimum Feulgen hydrolysis conditions.

1977 ◽  
Vol 25 (2) ◽  
pp. 129-134 ◽  
Author(s):  
P T Kjellstrand
Keyword(s):  
Temperature Dependence ◽  
Acid Concentration ◽  
Entire Range ◽  
Room Temperature ◽  
Reaction Rate ◽  
Maximum Amount ◽  
High Acid Concentration ◽  
Wide Range ◽  
Aldehyde Groups ◽  
Hydrolysis Conditions

Exposure and removal of aldehyde groups during Feulgen acid hydrolysis were studied at a wide range of temperature and acid concentrations. Temperatures between 9 and 75degreesC were found to influence only the rate of the hydrolysis reaction over the entire range from high (6 M) to low (0.05 M) HCl concentrations. The temperature dependence was high, and around +5degreesC was sufficient to double the reaction rate. The influence of acid concentrations between 0.02 and 6 M was studied, and the extraction rates that determine the peak values of the Feulgen hydrolysis curve were found to depend in the same way on the (H+) concentration. A diagram is given that makes it possible to determine the time to reach the point during hydrolysis where the maximum amount of aldehyde groups are developed for a wide range of temperatures and acid concentrations. Temperatures slightly above room temperature in combination with high acid concentration is recommended for Feulgen hydrolysis.

Thermoelectric Properties of Zn4-xSb3 with x=0~0.5

2007 ◽  
Vol 124-126 ◽  
pp. 1019-1022 ◽  
Author(s):  
K.W. Jang ◽  
Il Ho Kim ◽  
Jung Il Lee ◽  
Good Sun Choi
Keyword(s):  
Thermal Conductivity ◽  
Electrical Resistivity ◽  
Seebeck Coefficient ◽  
Temperature Dependence ◽  
Carrier Concentration ◽  
Thermoelectric Properties ◽  
Hall Mobility ◽  
Room Temperature ◽  
Vacuum Melting ◽  
Increasing Temperature

Non-stoichiometric Zn4-xSb3 compounds with x=0~0.5 were prepared by vacuum melting at 1173K and annealing solidified ingots at 623K. Electrical resistivity and Seebeck coefficient at 450K increased from 1.8cm and 145K-1 for Zn4Sb3(x=0) to 56.2cm 350K-1 for Zn3.5Sb3(x=0.5) due to the decrease of the carrier concentration. Hall mobility and carrier concentration was 31.5cm2V-1s-1 and 1.32X1020cm-3 for Zn4Sb3 and 70cm2V-1s-1 and 2.80X1018cm-3 for Zn3.5Sb3. Electrical resistivity of Zn4-xSb3 with x=0~0.2 showed linearly increasing temperature dependence, whereas those of Zn4-xSb3 with x=0.3~0.5 above 450 K tended to decrease. Thermal conductivity of Zn4Sb3 was 8.5mWcm-1K-1 at room temperature and that of Zn4-xSb3 with x≥0.3 was around 11mWcm-1K-1. Maximum ZT of Zn4Sb3 was obtained around 1.3 at 600K. Zn4Sb3 with x=0.3~0.5 showed very small value of ZT=0.2~0.3.

The chemical interpretation and the temperature dependence of the 14N nuclear quadrupole resonance of aniline and several derivatives

1968 ◽  
Vol 46 (22) ◽  
pp. 3595-3604 ◽  
Author(s):  
C. T. Yim ◽  
M. A. Whitehead ◽  
Donald H. Lo
Keyword(s):  
Temperature Dependence ◽  
Nuclear Quadrupole Resonance ◽  
Coupling Constants ◽  
Temperature Range ◽  
Resonance Frequencies ◽  
Quadrupole Coupling ◽  
Quadrupole Resonance ◽  
Nuclear Quadrupole ◽  
Asymmetry Parameters ◽  
Phenylene Diamine

The 14N nuclear quadrupole resonance frequencies of aniline, o- and p-phenylene diamine, and p-chloro-, p-bromo-, and p-iodo-aniline were measured with a super-regenerative oscillator over a temperature range from 77 to 292 °K. The temperature dependence is analyzed. The chemical interpretation of the quadrupole coupling constants and asymmetry parameters is described.

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