Estimation of lifetimes of solvent radical cations in liquid alkanes using the level crossing spectroscopy technique

The technique of radical ion pair level crossing spectroscopy was employed to obtain the electron spin resonance spectrum parameters of solvent radical cations for a series of linear nonviscous alkanes (pentane to hexadecane) at room temperature. The spectra consist of a single homogeneous line that becomes broader as the carbon chain of the alkane molecule becomes shorter. Effective hyperfine interactions in radical cations are negligible. The lower estimates for the lifetimes of radical cations were obtained. Assuming that the contribution of spin relaxation to the line width is not important, the lower estimates increase from 1 to 33 ns in the sequence C5–C16.