On the Nature of Electron Traps in Hydrocarbon Glasses at Low Temperatures

A delicate application of the EPR linewidth theory to the experimentally measured trapped electron (e^?_?) linewidths in three kinds of isotopic 3-methyl-pentane molecules (3MP) concludes that the electron traps are formed by the protons regardless of their relative positions in the molecule. With the cavity radius of <2 Å, the trapped electron charge density in these nonpolar hydrocarbon glasses is shown to be highly delocalized. The slower thermal decay rate of e^?_? 3MP_d14 than in 3MP_h14 is most likely related to the deeper trap depth in the former than in the latter leading to a predicted blue shift absorption peak for e^?_? in 3MP_d14 relative to that in 3MP_h14 The farther travel distance for mobile electrons before being trapped in these matrices than in polar matrices is attributed to the low trapping cross section rather than a low trap density. Consistency of the empirical cavity radius with the predicted value from current theoretical basis is also cited.