Manifestation of quantum coherence upon recombination of radical ion pairs in weak magnetic fields. Systems with equivalent nuclei

Magnetic Field Effects on Radical Pairs in Homogeneous Solution

“…8.8). In such systems, those pairs with large HFCs in one pair member and negligible couplings in the other produce the strongest LFEs in good agreement with previous prediction 47,48 and the short lifetime regime found in the theoretical screening work. 49 The presence of substantial LFEs also causes a problem for the useful MARY B 1/2 FIGURE 8.8 Magnetic field dependence for the photolysis of a series of benzoyl containing molecules in cyclohexanol solution obtained by time-resolved infrared spectroscopy of the carbonyl group of the resulting benzoyl radical.…”

“…Early experimental and theoretical studies concluded that substantial LFEs are only observed for RPs in which there are substantial HFCs in one pair member and negligible couplings in the other. 47,48 In a more recent study, RPs with a wide range of combinations of HFCs and lifetime were screened for LFEs by simulation on a supercomputer. 49 This study concluded that indeed for short-lived RPs, the large:small HFC combination is required to produce substantial LFEs, but for long-lived RPs the restriction vanishes.…”

Specific MARY spectrum from radical anion of pentafluorobenzene

“…It is appropriate to acknowledge that K. M. Salikhov and colleagues [2,3] demonstrated that systems with equivalent nuclei, such as radical anion of hexafluorobenzene, can in principle produce observable lines in nonzero fields -multiples of the single HFC constant AHF. Although much weaker than the ubiquitous zero-field line, these "satellite" lines were then indeed observed experimentally [4,5], and even richer spectra were reported later [6]. The uniqueness of systems with equivalent nuclei lies in a very regular energy level layout governed by just one parameter AHv, so that the crossings for them also occur at regular, well-defined places and thus lend themselves to experimental observation.…”

Magnetic field modulation of the delayed fluorescenceyield in the photoionization reaction of N, N, N′, N′‐tetramethyl‐p‐phenylenediamine in water

“…In some cases however the RIP's lifetime is long enough for effective spin mixings but the detection methods are too slow to register or/and insensitive to very small variations accompanying these spin mixings. Introduction of the modulation technique to the methods of detection of MFEs introduced much better signal-to-noise ratio and higher time resolution to the detection of radical pairs in solution [9,10,12]. MARY (MAgnetic field modulation of the Reaction Yield) spectra, or more precisely the MFEs on the recombination fluorescence yield, exhibit relatively narrow lines.…”