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7731017 
Journal Article 
Gamma-ray spectra of hexane (C6H14) in positron-electron annihilation process 
Ma, X; Wang, F 
2013 
1 
Radiation Physics and Chemistry
ISSN: 0969-806X 
PERGAMON-ELSEVIER SCIENCE LTD 
OXFORD 
89 
14-19 
English 
WOS:000320750100002 
Theoretical gamma-ray spectra of molecule hexane have been calculated and compared with the experimental results in both gas (Iwata et al., 1997a) and liquid (Kerr et al., 1965) phases. The present study reveals that in gas phase not all valence electrons of hexane contribute the same degree in the electron-positron annihilation of hexane. The electrons which dominate the positron-electron annihilation of molecules are called positrophilic electrons. The positrophilic electrons are predominately found to involve the electrons on the lowest occupied valence orbital (LOVO) of a free molecule in gas phase. When hexane is confined in liquid phase, however, the intermolecular interactions ultimately eliminate the free molecular orientation and selectivity for the positrophilic electrons in the gas phase. As a result, the gamma-ray spectra of hexane become an "averaged" contribution from all valence electrons, which is again in agreement with liquid phase measurement. The roles of valence electrons in annihilation process for gas and liquid phases of hexane have been recognized for the first time in the present study. © 2013 Elsevier Ltd. 
Gamma-ray spectra of hexane; Positron-electron annihilation; Positrophilic electrons; Lowest occupied valence orbital (LOVO)