Study on the Tunneling Reaction of H Atoms with a Solid Thin Film of C₃H₆ at 10 K

Abstract

The reaction of the solid thin film of propene (C 3 H 6 ) deposited on the silicon substrate at 10 K with cold H atoms (∼27 K) sprayed over the solid films was studied. Propane and 2-methylpentane were found to be the major and minor reaction products, respectively. The rate for the formation of C 3 H 8 increased steeply with a decrease of temperature from 35 to 10 K. This is the general trend for the low-temperature tunneling reactions investigated in our laboratory. With an increase of temperature from 40 to 55 K, the yield of C 3 H 8 showed a slow increase. This may be due to the replenishment of the reactant C 3 H 6 molecules to the surface above ∼40 K (i.e., solid-phase diffusion). The yield of C 3 H 8 from C 3 H 6 was lower than that of C 2 H 6 from C 2 H 4 . This may be due either to the hindrance of the proximity approach of the H atom to the C 3 H 6 double bond by the presence of the methyl group and/or to the annihilation of the H atoms by the H-atom abstraction reaction with the reaction product C 3 H 8 to form the s-C 3 H 7 radical on the surface of the solid film.

Solid‐Phase Reactions of D with CN to Form DNC and DCN at Cryogenic Temperatures

“…The general experimental procedures were similar to those described previously (Hiraoka et al 2002a(Hiraoka et al , 2002b(Hiraoka et al , 2005. The cryocooler (Iwatani Plantech, type D310) was housed in a vacuum manifold.…”

“…The pressure of the reagent gas in the discharge tube was about 2 torr. The discharge tube shown in Figure 1 does not have the electrodes for the electron trap that were used in our previous work (Hiraoka et al 2002a(Hiraoka et al , 2002b(Hiraoka et al , 2005. When the bottleneck discharge tube with electrodes was used, the metal electrodes installed inside the discharge tube were quickly contaminated by the radiation products, and the plasma became unstable after some time of operation.…”

Methanol Formation from Electron‐irradiated Mixed H2O/CH4Ice at 10 K

“…Hiraoka et al (2002aHiraoka et al ( , 2005 studied the tunneling reactions of H with CO and H 2 CO. They found that the rates of reactions of H with CO and H 2 CO are relatively much smaller than those with C 2 H 4 (Hiraoka et al 2000), C 3 H 6 (Hiraoka et al 2002b), C 2 H 2 (Hiraoka et al 2000), and SiH 4 (Hiraoka et al 2001). They concluded that the grain-surface reaction [ H þ CO] may not be the major source for the ubiquitous methanol in the ISM.…”

Low-temperature reactions in the chemistry of nanosystems

“…The possibility of using tunnelling reactions of hydrogen atoms for hydrogenation of various organic and inorganic compounds under conditions of cryochemical synthesis has been considered. 142,143 Experiments carried out at 10 K showed that cyclic olefins (cyclopentene and cyclohexene) nearly instantaneously (in a few seconds) react with hydrogen atoms to give the corresponding cyclic alkanes. 142,143 The reaction of hydrogen atoms with solid CO results in quantitative yields of formaldehyde and methanol.…”

“…142,143 Experiments carried out at 10 K showed that cyclic olefins (cyclopentene and cyclohexene) nearly instantaneously (in a few seconds) react with hydrogen atoms to give the corresponding cyclic alkanes. 142,143 The reaction of hydrogen atoms with solid CO results in quantitative yields of formaldehyde and methanol. 144 The last-mentioned compound is efficiently formed upon additional UV irradiation of the system.…”