Kinetic study of the gas-phase reaction of Ca(1S0) with O2 from 296 to 623 K

被引:9
作者
Campbell, ML [1 ]
Plane, JMC
机构
[1] USN Acad, Dept Chem, Annapolis, MD 21402 USA
[2] Univ E Anglia, Sch Environm Sci, Norwich NR4 7TJ, Norfolk, England
关键词
D O I
10.1021/jp003808e
中图分类号
O64 [物理化学(理论化学)、化学物理学];
学科分类号
070304 ; 081704 ;
摘要
The reactivity of gas-phase ground-state calcium atoms with O-2 is reported from 296 to 623 K, Calcium atoms were produced by the photodissociation of Ca(FOD)(2) [where FOD represents the 6,6,7.7,8,8,8-heptafluoro-2,2-dimethyl-3,5-octanedionate ion] and detected by laser-induced fluorescence. Calcium recombines with O-2 to form CaO2 in a reaction that exhibits a positive temperature dependence and is significantly in the falloff region even at pressures as low as 10 Torr. Ab initio quantum calculations are used to show that the reaction most likely proceeds on a tripler surface, where the Ca atom inserts into the O-O bond to form a triplet dioxide (B-3(2)) With a very low frequency bending mode. The surprisingly large rate coefficient at elevated temperatures is explained by the correspondingly high density of rovibrational states, and the positive temperature dependence by a small barrier in the entrance channel at the crossing point between the covalent and ionic diabats. RRKM theory, fitted to the experimental data, predicts the following expression for the rate coefficient from 140 to 1000 K and 10(-5) to 10(3) Torr: log(k(rec.0)/cm(6) molecule(-1) s(-1)) = -57.20 + 19.70 log T - 3.410(log T)(2), k(rec,infinity) = 1.36 x 10(-10) exp(-1020/T) cm(3) molecule(-1) s(-1), and F-c = 0.67.
引用
收藏
页码:3515 / 3520
页数:6
相关论文
共 16 条
[1]   REACTIONS OF PULSED-LASER EVAPORATED CA, SR, AND BA ATOMS WITH O-2 - INFRARED-SPECTRA OF THE METAL-OXIDES, OXIDE DIMERS, DIOXIDES, AND PEROXIDES IN SOLID ARGON [J].
ANDREWS, L ;
YUSTEIN, JT ;
THOMPSON, CA ;
HUNT, RD .
JOURNAL OF PHYSICAL CHEMISTRY, 1994, 98 (26) :6514-6521
[2]   Infrared spectra and quantum chemical calculations of group 2 MO(2), O(2)MO(2), and related molecules [J].
Andrews, L ;
Chertihin, GV ;
Thompson, CA ;
Dillon, J ;
Byrne, S ;
Bauschlicher, CW .
JOURNAL OF PHYSICAL CHEMISTRY, 1996, 100 (24) :10088-10099
[3]   THEORETICAL-STUDY OF THE ALKALINE-EARTH METAL SUPEROXIDES BEO2 THROUGH SRO2 [J].
BAUSCHLICHER, CW ;
PARTRIDGE, H ;
SODUPE, M ;
LANGHOFF, SR .
JOURNAL OF PHYSICAL CHEMISTRY, 1992, 96 (23) :9259-9264
[4]   TEMPERATURE-DEPENDENT STUDIES OF THE REACTION OF W(A D-5(J), A S-7(3)) WITH O-2 [J].
CAMPBELL, ML ;
MCCLEAN, RE .
JOURNAL OF THE CHEMICAL SOCIETY-FARADAY TRANSACTIONS, 1995, 91 (21) :3787-3793
[5]  
Foresman J., 2015, Exploring Chemistry with Electronic Structure Methods, V3rd
[6]  
Frisch M.J., 2016, Gaussian 16 Revision C. 01. 2016, V16, P01
[7]   Atmospheric Ca and Ca+ layers:: Midlatitude observations and modeling [J].
Gerding, M ;
Alpers, M ;
von Zahn, U ;
Rollason, RJ ;
Plane, JMC .
JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS, 2000, 105 (A12) :27131-27146
[8]  
GILBERT RG, 2000, THEORY UNIMOLECULAR
[9]   UNUSUAL KINETIC-BEHAVIOR OF THE REACTIONS MG+O2+M AND CA+O2+M(M=N2,HE) OVER EXTENDED TEMPERATURE RANGES [J].
NIEN, CF ;
RAJASEKHAR, B ;
PLANE, JMC .
JOURNAL OF PHYSICAL CHEMISTRY, 1993, 97 (24) :6449-6456
[10]  
Pereira RD, 1997, J PHYS CHEM A, V101, P9681