Electron Paramagnetic Resonance Absorption in Oxygen with the HCN Laser

Early Epr in Some Gases

“…Laser EPR in gases. In 1968-1971, demonstrations of laser EPR showed the higher sensitivity available from the detection of photons in the optical range as reported by Evenson and coworkers (38)(39)(40). Laser EPR measurements of the N0 2 molecule's couplings with improved sensitivity were reported in 1972 (41).…”

Instrumentation for THz Spectroscopy in the Laboratory and in Space

“…This has been used successfully with ions in the infrared [20] but has not been demonstrated at longer wavelength. The second technique is to Zeeman shift a transition into resonance with the laser [21]. This generally requires that the molecule be paramagnetic, which produces a significant interaction between magnetic field and the magnetic moment of the unpaired electron(s), allowing the magnetic field to alter the energy of the state.…”

“…A number of spectroscopic techniques were developed to shift the molecular transition frequency into resonance with a laser including Doppler shifting [20], Zeeman shifting (Laser Magnetic Resonance or LMR) [21] , and Stark shifting (Laser Stark) [22]. A number of methods to generate tunable radiation were developed including laser sideband [23], tunable klystrons [24], tunable backward-wave oscillators (BWOs) [25], tunable far-infrared (TuFIR) [26], and optical difference frequency generation (photomixing) [27].…”

Molecular Spectroscopy: Some Personal Reminiscences

“…Apart from these two fundamental developments, there have been sev eral important advances in technique. In the late 1960s, laser magnetic resonance was introduced (144) and has been very successful in detecting transient species both in the far and near infrared. In 1980, the first infrared spectrum of a molecular ion, H;, was obtained (145), and five years later, the first infrared spectrum of a negative molecular ion was reported (146).…”