Showing papers by "Xiang Zhang published in 1993"
TL;DR: In this paper, the production of the [chi][sub 1] and [chi]-sub 2] states of charmonium has been observed in 300 GeV/[ital c] [pi][sup [plus minus]][ital N] interactions and [ital pN] interactions.
Abstract: The production of the [chi][sub 1] and [chi][sub 2] states of charmonium has been observed in 300 GeV/[ital c] [pi][sup [plus minus]][ital N] and [ital pN] interactions. The fraction of the total inclusive [ital J]/[psi] production due to radiative [chi] decay has been determined to be 0.40[plus minus]0.04, 0.37[plus minus]0.03, and 0.30[plus minus]0.04 for the [pi][sup +], [pi][sup [minus]], and proton data, respectively. Total cross sections have been obtained of 131[plus minus]18[plus minus]14 and 188[plus minus]30[plus minus]21 nb/nucleon in the 300 GeV/[ital c] [pi][sup [minus]][ital N] interactions for [chi][sub 1] and [chi][sub 2] production. By measuring the contributions to the [ital J]/[psi] production due to both [psi][prime] and radiative [chi] decay, the cross sections for direct [ital J]/[psi] production have been determined to be 97[plus minus]14, 102[plus minus]14, and 89[plus minus]12 nb/nucleon for [pi][sup +], [pi][sup [minus]], and protons, respectively.
61 citations
TL;DR: In this paper, the reaction of seven N-acyl indole derivatives with singlet oxygen was investigated and the results showed that 1-acetyl-(2a) and 1-(chloroacetyl)-2-hydroperoxy-3-methyleneindoline (2b) gave high yields via ene reaction on irradiation with oxygen in the presence of TPP sensitizer.
Abstract: Reactions of seven N-acyl indole derivatives with singlet oxygen have been investigated. 1-Acetyl-(1a) and 1-(chloroacetyl)-2,3-dimethylindole (1b) gave exclusively 1-acetyl-(2a) and 1-(chloroacetyl)-2-hydroperoxy-3-methyleneindoline (2b), respectively, in high yields via ene reaction on irradiation with oxygen in the presence of TPP sensitizer. 1-Acetyl-3-methylindole (1c) gave only 1-acetyl-2-hydroperoxy-3-methyleneindoline (2c) in low yield under the same conditions
38 citations
TL;DR: In this article, two different strain relief mechanisms, directly associated with (110) surface geometry, were observed in the two orthogonal directions [1 1 0] and [001], and the density of the latter was film thickness dependent.
36 citations
TL;DR: A series of 1-methyl and 1-(phenylsulfonyl)-substituted 3-vinylindoles with different electronic and steric features has been synthesized and their sensitized photooxygenation in aprotic solvents investigated as mentioned in this paper.
Abstract: A series of 1-methyl- and 1-(phenylsulfonyl)-substituted 3-vinylindoles with different electronic and steric features has been synthesized and their sensitized photooxygenation in aprotic solvents investigated. 1-Methyl-3-vinyl-(1a), 1,2-dimethyl-3-vinyl-(1b), 1-methyl-3-(α-methoxyvinyl)- (4-Z and 4-E, 1-(phenylsulfonyl)-3-vinyl-(8b), 1-(phenylsulfonyl)-3-(α-methylvinyl) (8b), 1-(phenylsulfonyl)-3-(α-methoxyvinyl)- (8c and 8d), and cis-1-(phenylsulfonyl)-3-(α-methyl-β-methoxyvinyl) indoles (1d-Z) react with 1 O 2 predominantly to give endoperoxides via [4+2] cycloaddition. However, 1,2-dimethyl-3-(β-methoxyvinyl)indole (1c) gives [2+2] cycloaddition with the 3-double bond to give 1,2-dimethyl-3-formylindole (3c); trans-1-(phenylsulfonyl)-3-(α-methyl-β-methoxyvinyl)indole (15-E) gives the 3-indolyl allylic hydroperoxide (17) via ene reaction, along with a small amount of isomerization of the 3-vinyl double bond. A zwitterionic intermediate in the isomerization is proposed. Most of the resulting dioxacarbazole endoperoxides are isolable and inert to reduction by trimethyl phosphite and thiourea except for N-methyldioxacarbazole 5, which undergoes clean rearrangement to indolin-2-one epoxide 7 at -20°C
16 citations
TL;DR: In this article, the epitaxial growth of Si and Si x Ge 1-x alloys from molecular beams of gaseous Si (Si 2 H 6 ) and Ge (GeH 4 ) hydrides on Si (001) substrates (Si-GSMBE) has been studied using reflection high energy electron diffraction (RHEED) Diffraction patterns reveal that Ge deposited on Si results in a Stranski-Krastanow growth mode with a change in surface reconstruction in the two-dimensional (2D) regime from the twodomain Si(001
8 citations
TL;DR: In this paper, the reaction of seven N-acyl indole derivatives with singlet oxygen was investigated and the results showed that 1-acetyl-(2a) and 1-(chloroacetyl)-2-hydroperoxy-3-methyleneindoline (2b) gave high yields via ene reaction on irradiation with oxygen in the presence of TPP sensitizer.
Abstract: Reactions of seven N-acyl indole derivatives with singlet oxygen have been investigated. 1-Acetyl-(1a) and 1-(chloroacetyl)-2,3-dimethylindole (1b) gave exclusively 1-acetyl-(2a) and 1-(chloroacetyl)-2-hydroperoxy-3-methyleneindoline (2b), respectively, in high yields via ene reaction on irradiation with oxygen in the presence of TPP sensitizer. 1-Acetyl-3-methylindole (1c) gave only 1-acetyl-2-hydroperoxy-3-methyleneindoline (2c) in low yield under the same conditions
3 citations