General trends of positronium pick-off annihilation in molecular substances

被引:29
作者
Dutta, D
Ganguly, BN
Gangopadhyay, D
Mukherjee, T
Dutta-Roy, B
机构
[1] Saha Inst Nucl Phys, Kolkata 700064, W Bengal, India
[2] Bhairab Ganguly Coll, Dept Phys, Kolkata 700056, India
[3] SN Bose Natl Ctr Basic Sci, Kolkata 700098, India
关键词
D O I
10.1088/0953-8984/14/32/313
中图分类号
O469 [凝聚态物理学];
学科分类号
070205 ;
摘要
The characteristics of positronium (Ps) annihilation in molecular substances (ranging from organic liquids to molecular solids), manifested through the observed lifetimes (tau(p)) for the 'pick-off' process and values of angular correlation (theta(1/2)) of decay gammas, can be shown to be simply related to the size (radius R) of the cavity which the Ps creates in a liquid or finds in a molecular solid. The measured tau(p) and theta(1/2) are in turn calculable from the wavefunction describing the Ps centre-of-mass motion, which is determined from the average potential experienced by it in the confining cavity. Thus the height of this repulsive barrier (U-0) at the wall of this vacant region corresponding to different materials (with varying R) can be obtained by fitting experimental observations, namely tau(p) and theta(1/2). The model we use is an improved version of the usual spherical well description of the cavity (where we take the walls to be diffuse). It is found that the values of U-0 and R, taking into account all available and relevant data for different molecular substances, fall on a universal curve. We attempt to explain the reason behind this 'universality' by relating the potential to the Ps work-function in materials. Finally, the fit provides us with a very convenient linear relationship between the size (R) of the cavity and the pick-off lifetime (tau(p)).
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页码:7539 / 7549
页数:11
相关论文
共 42 条
  • [1] RELAXED POSITRONIUM IN POLYMERS
    BERTOLAC.M
    BISI, A
    GAMBARIN.G
    ZAPPA, L
    [J]. JOURNAL OF PHYSICS C-SOLID STATE PHYSICS, 1974, 7 (21): : 3827 - 3832
  • [2] ELECTRIC-FIELD DEPENDENCE OF POSITRONIUM FORMATION IN CONDENSED MATTER
    BRANDT, W
    WILKENFELD, J
    [J]. PHYSICAL REVIEW B, 1975, 12 (07) : 2579 - 2587
  • [3] BYAKOV VM, 1983, RADIOCHEM RADIOA LET, V58, P91
  • [4] ON THE ORIGIN OF THE INTERMEDIATE COMPONENT IN THE POSITRON LIFETIME SPECTRA IN POLYMERS
    CONSOLATI, G
    QUASSO, F
    [J]. APPLIED PHYSICS A-MATERIALS SCIENCE & PROCESSING, 1990, 50 (01): : 43 - 48
  • [5] POSITRON ANNIHILATION IN HELIUM
    DANIEL, TB
    STUMP, R
    [J]. PHYSICAL REVIEW, 1959, 115 (06): : 1599 - 1600
  • [6] Trapping of positronium in a size-dependent spherical square well potential
    Dauwe, C
    Balcaen, N
    Van Petegem, S
    Segers, D
    [J]. RADIATION PHYSICS AND CHEMISTRY, 2000, 58 (5-6) : 681 - 685
  • [7] DAUWE C, 1999, COMMUNICATION
  • [8] Dupasquier A, 1983, POSITRON SOLID STATE, P510
  • [9] THE TEMPERATURE-DEPENDENCE OF POSITRON LIFETIMES IN SOLID PIVALIC ACID
    ELDRUP, M
    LIGHTBODY, D
    SHERWOOD, JN
    [J]. CHEMICAL PHYSICS, 1981, 63 (1-2) : 51 - 58
  • [10] POSITRON-ANNIHILATION STUDY OF DEFECTS IN SUCCINONITRILE
    ELDRUP, M
    PEDERSEN, NJ
    SHERWOOD, JN
    [J]. PHYSICAL REVIEW LETTERS, 1979, 43 (19) : 1407 - 1410