Amounts of D and H atoms, produced by y-radiolysis of D2-n-H2( 1 mol %) mixtures, were measured at 4.2 or 1.9 K by ESR. The amounts of D atoms decay upon storage of the irradiated sample at 4.2 K up to 114 h, while those of H atoms are nearly constant. The results were interpreted in terms of competition of a tunneling reaction n-H2 + D -H + HD with combination reactions of D and H atoms. Similar decay behaviors of D and H atoms were also observed in D2-pH2(1 mol 96) mixtures at 4.2 K and D2-n-Hz( 1 mol %) mixtures at 4.5 K. The rate constant for the tunneling reaction n-H2 + D + H + HD was estimated from a kinetic treatment of the decay behavior. It was found that the rate constant is expressed by two ranges of values: 2.7 X 10-'-4.9 X 10-' cm3 mol-' S-I and 3.9 X 10-4-2.6 X lC3 cm3 mol-' s-'. The different values of the rate anstant arc related probably to internal rearrangements of reactive spbcies in solid hydrogen at ultralow temperature.The experimental rate constant for the tunneling reaction n-Hz + D -H + HD was compared with the theoretical ones reported previously.
The method developed to analyze the components of cigarette odors is capable of quantitatively evaluating lingering odor using a simple procedure. The odor intensity is then estimated by condensing the gas evaporated from curtain material previously exposed to cigarette odors and subsequently analyzing the gas with gas chromatograph mass spectrometry. The lingering odor has been confirmed to contain aldehyde, olefin, heterocyclic and heteroaromatic compounds. After confirming the linear correlation between the logarithm of vinyl pyridine concentration and the six-level odor intensity, a simplified method of estimating the intensity of lingering odors has become possible by using the vinyl pyridine concentration.
The ESR linewidths of H(D) atoms, produced in γ-irradiated solid hydrogen, depend significantly upon the matrices of the hydrogen isotopes. The ESR linewidth has been calculated by considering the dipole interactions of the electron spin magnetic moments of a trapped hydrogen atom with the nuclear magnetic moments of the surrounding hydrogen nuclei in addition to the Fermi interactions. It is concluded from a comparison of the experimental ESR linewidths with the theoretical ones that the H atoms in solid H2 are trapped at substitutional sites, while the H(D) atoms in solid HD and D2 are trapped at interstitial octahedral sites.
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