Abstract
Both lifetime and angular correlation of positron annihilation have been measured for a series of synthetic zeolites for which the void structures are known fairly well. All of the zeolites had long lifetime components and a narrow momentum component which are ascribable to o-Ps and p-Ps annihilations in the voids, respectively. The correlation between the width of the p-Ps narrow component and the size of the largest voids showed a remarkable agreement with a theoretical estimate based on the spherical potential well model. The measurement of p-Ps momentum thus appears to be prospective as a tool to determine the size of voids of materials. The lifetime of the long lifetime component, on the other hand, showed a poor correlation with the void size even from a qualitative viewpoint, suggesting that factors other than the simple void size effect are dominant in determining the o-Ps lifetimes. Discussion is made on the cause of the different dependences of o-Ps and p-Ps annihilation parameters on the void size. It has also been found that p-Ps fraction is always larger than one third of the o-Ps fraction in all the zeolites studied. A discussion is presented on this point, too.
Similar content being viewed by others
References
Typical PA studies of zeolites are: M.B. Perkal, W.B. Walters: J. Chem. Phys.53, 190 (1970)
Typical PA studies of zeolites are: H. Nakanishi, Y. Ujihira: J. Phys. Chem.86, 4446 (1982)
Typical PA studies of zeolites are: B.M. Levin, V.P. Shantarovich, D.A. Agievskii, M.B. Landau, G.D. Chukin: Kinetika i Kataliz18, 1542 (1977)
Typical PA studies of silica gels are: S.Y. Chuang, S.J. Tao: J. Chem. Phys.54, 4902 (1971)
Typical PA studies of silica gels are: S.Y. Chuang, S.J. Tao: Can. J. Phys.51, 820 (1973)
Typical PA studies of silica gels are: F.R. Steldt, P.G. Varlashkin: Phys. Rev. B5, 4265 (1972)
C.V. Briscoe, S.I. Choi, A.T. Stewart: Phys. Rev. Lett.20, 493 (1968)
J.P. Hernandez, S.I. Choi: Phys. Rev.188, 340 (1969)
J.H. Kusmiss, Stewart, A.T.:Positron Annihilation ed. by A.T. Stewart, L.O. Roellig (Academic, New York 1966) p. 341
V.I. Goldanskii, A.D. Mokrushin, A.O. Tatur, V.P. Shantarovich: Kinetika i Kataliz13, 961 (1972)
The data on the structure of zeolites are taken from the following references R.M. Barrer:Zeolites and Clay Minerals as Sorbents and Molecular Sieves (Academic, New York 1978)
The data on the structure of zeolites are taken from the following references D.W. Breck:Zeolite Molecular Sieves, Structure, Chemistry, and Use (Wiley, New York 1974)
A.M. Cooper, G.J. Laidlaw, B.G. Hogg: J. Chem. Phys.46, 2441 (1967)
M. Hasegawa, Y.J. He, K.R. Hoffmann, R.R. Lee, S. Berko:Positron Annihilation (Proc. 7th Int. Conf. Positron Annihi-lation), ed. by P.C. Jain, R.M. Singru and K.P. Gopinathan (World Scientific, 1985) p. 260
A.P. Buchikin, V.I. Goldanskii, A.V. Tatur, V.P. Shantarovich: Zd. Eksp. Theor. Fiz.60, 1136 (1971)
M. Tsuchiya, M. Hasegawa: To be published
W. Brandt, R. Paulin: Rev. Lett.21, 103 (1968)
W. Brandt, S. Berko, W.W. Walker: Phys. Rev.120, 1289 (1960)
O.E. Mogensen, F.M. Jacobsen: Chem. Phys.73, 223 (1982)
O.E. Mogensen, N.J. Pedersen: Chem. Phys.87, 139 (1984)
R.L. Klobuchar, P.J. Karol: J. Phys. Chem.84, 483 (1980)
J. Lee, G.J. Celitans: J. Chem. Phys.44, 2506 (1966)
A.D. Mokrushin, A.O. Tatur, V.P. Shantarovich: Izd. Akad. Nauk SSSR, Ser. Khim.6, 1216 (1973)
S.Y. Chuang, S.J. Tao: Appl. Phys.3, 191 (1974)
F.K. Kiefl:Positron Annihilation ed. by P.G. Coleman, S.C. Sharma, L.M. Diana (North-Holland, Amsterdam 1982) p. 690
In a recent measurement over a longer time range, which will be published in a forthcoming paper, we could indeed observe an additional component much longer than 50 ns. But its fraction was small: 1.9% for sodalite, 4.9% for ZSM-5, etc.
Author information
Authors and Affiliations
Additional information
Formerly, RIISOM