Decay of hydrogen(deuterium) atoms in solid hydrogen at 4.2 K: rate constant for tunneling reaction hydrogen (deuterium, hydrogen deuteride) + hydrogen (deuterium) atom

1989 ◽  
Vol 93 (8) ◽  
pp. 3352-3355 ◽  
Author(s):  
Tetsuo Miyazaki ◽  
Nobuchika Iwata ◽  
Kwang Pill Lee ◽  
Kenji Fueki
Keyword(s):  
Rate Constant ◽  
Deuterium Atom ◽  
Solid Hydrogen ◽  
Hydrogen Deuteride ◽  
Hydrogen Deuterium

Pressure effect on hydrogen isotope exchange kinetics in chymotrypsinogen investigated by FT-IR spectroscopy

1991 ◽  
Vol 69 (11) ◽  
pp. 1699-1704 ◽  
Author(s):  
P. T. T. Wong
Keyword(s):  
High Pressure ◽  
Exchange Rate ◽  
Rate Constant ◽  
Bound Water ◽  
Pressure Effects ◽  
Protein Molecules ◽  
Fast Exchange ◽  
Exchange Rate Constant ◽  
Hydrogen Deuterium ◽  
Exchange Kinetics

Hydrogen/deuterium (H/D) exchange rate constants in chymotrypsinogen have been determined at several pressures up to 28.9 kbar by FTIR spectroscopy. The secondary structure of the protein molecules was monitored simultaneously at the corresponding pressures by the intensity redistribution of the infrared amide I band at these pressures. As in other proteins, the labile protons on the amide groups in chymotrypsinogen can, to a good approximation, be separated into two classes, each with distinct first order H/D exchange rates constants in the time period from 10 min to ~24 h. The fast exchange rate constant increases while the slow exchange rate constant decreases with increasing pressure. The increase in the fast exchange rate constant at high pressure is largely associated with the pressure-induced unfolding of the protein molecules. At extremely high pressure (12.8 kbar), in addition to the unfolding of protein molecules, pressure induced a distortion and weakening of the hydrogen bonds of the fold protein segments also contribute to an increase in the overall H/D exchange rate. The present results confirm that when chymotrypsinogen is dissolved in D2O, a considerable amount of D2O molecules is bound to the protein molecules on the surface as well as in the interior cavities of the molecules. The H/D exchange takes place between these bound D2O and the protons in the protein molecules. The mechanism of the H/D exchange and the interior dynamics in proteins are discussed on the basis of the present results. Key words: hydrogen/deuterium exchange, exchange kinetics, rate constant, pressure effects, infrared spectroscopy, protein, conformation structure, bound water.

Microwave Enhanced Hydrogenation Reactions using Solid Hydrogen, Deuterium and Tritium Donors

1998 ◽  
pp. 400-401 ◽  
Author(s):  
Mohammed H. Al-Qahtani ◽  
Nicola Cleator ◽  
Timothy N. Danks ◽  
Russell N. Garman ◽  
John R. Jones ◽  
...  
Keyword(s):  
Solid Hydrogen ◽  
Hydrogenation Reactions ◽  
Hydrogen Deuterium

Muon molecular formation and transfer rate in solid hydrogen-deuterium mixtures

1996 ◽  
Vol 101-102 (1) ◽  
pp. 239-248 ◽  
Author(s):  
R. Jacot-Guillarmod ◽  
J. M. Bailey ◽  
G. A. Beer ◽  
J. L. Beveridge ◽  
M. C. Fujiwara ◽  
...  
Keyword(s):  
Transfer Rate ◽  
Solid Hydrogen ◽  
Molecular Formation ◽  
Hydrogen Deuterium

Hydridization and catalysis by lanthanide films

1984 ◽  
Vol 393 (1805) ◽  
pp. 257-276 ◽  
Keyword(s):  
Activation Energy ◽  
High Vacuum ◽  
Deuterium Atom ◽  
Ultra High Vacuum ◽  
Gas Uptake ◽  
Metal Sublattice ◽  
Hydrogen Deuterium ◽  
Higher Temperature ◽  
Temperature Programmed ◽  
Interstitial Hydrogen

Hydrogen absorption to give the dihydrides MH 2+1 containing interstitial hydrogen H i has been studied for the metals Gd, Dy, Er, Yb and Lu in the form of films deposited in ultra-high vacuum on glass. Film areas were determined by Kr adsorption, and hydrogen content, in particular inter­stitial hydrogen H i , characterized by gas uptake, temperature programmed desorption, electrical conductivity and work function measurements by the diode method. The catalytic activity of the dihydride films for the H 2 + D 2 → 2HD reaction was studied at a pressure of 1.1 Torr over 175-579 K, and at 273 K over 0.19-6.2 Torr. Arrhenius plots for the rate con­stant show a low temperature low activation energy region changing over at a temperature T c to a higher temperature higher activation energy régime, with T c on average for the five metals about 50 K below the tem­perature T max at which the interstitial hydrogen H i has disappeared. The suggested mechanisms are T < T c : D 2 + H i □ s → (D 2 H i )□ s → □ s D i + HD, (1) T > T c : D 2 + H 2 + 4□ s → 2(D i □ s ) (H i □ s ) → 4□ s + 2HD, (2) where H i □ s , D i □ s , denotes a hydrogen, deuterium, atom held on a surface octahedral site in the f. c. c. metal sublattice. These mechanisms agree with the observed approximate first-order pressure dependency down to 77 K. The rate constants at both 273 K (under T c ) and 573 K (over T c ) decrease over Gd, Dy, Er, to Yb, and rise again to Lu, and this is discussed in terms of the metal-hydrogen, H i □ s or D i □ s bond strength.

Sign in / Sign up

Export Citation Format

Share Document