ESR absorption of cesium and rubidium solutions in ethylamine

Electron spin resonance absorption spectra of cesium and rubidium solutions in ethylamine have been observed at temperatures between -29° and +23°C. These spectra are characterized by a sharp single-line resonance near the center of a hyperfine pattern. The lines of a hyperfine pattern vary in amplitude and breadth. The larger amplitude, narrower lines lie near the center of the spectrum. The hyperfine patterns are attributed to ⁸⁵Rb and ¹³³0Cs nuclei interacting with an unpaired electron. The spin density at the ⁸⁵Rb nucleus varies from 1.05±0.1×10 ²⁴ cm³ at -25°C to 1.90±0.05×1024 cm ³ at 23°C and at the ¹³³Cs nucleus from 2.29±0.03×10²⁴ cm³ at -29°C to 2.80±0.03×10²⁴ cm³ at -10°C. The variations in Une breadths are interpreted in terms of the structure of the metal monomer. The difference in g values between the singleline resonance and the hyperfine pattern is attributed to spin-orbit coupling in the monomer and structural implications are discussed. The single-line resonance is assigned to the solvent anion, i.e., the solvated electron.