The low energy phonon modes of the hydrogenated and deuterated π-conjugated system 7,7,8,8-tetracyanoquinodimethane: an inelastic neutron scattering study

Berlie, Adam; Cavaye, Hamish

doi:10.1039/d0cp06253g

Cited by 1 publication

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“…The resonance peaks were clearly observable at low temperatures; however at 298 K, the intensity was extremely weak. This loss of intensity is expected because at high temperatures, there is a significant population of low energy vibrational modes 35 that cause distortions of the TCNQ molecule and these will be expected to smear out the interactions between the muon and the 14 N nuclei.…”

Section: ■ Experimental Resultsmentioning

confidence: 99%

Muon–Nitrogen Quadrupolar Level Crossing Resonance in a Charge Transfer Salt

et al. 2022

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Although muons are primarily regarded as a local spin probe, they can also access the charge state of an atom or molecule via quadrupolar level crossing resonance (QLCR) spectroscopy. We use Li + TCNQ – (TCNQ = 7,7,8,8-tetracyanoquinodimethane), a simple charge transfer salt, to test the potential of this technique in molecular systems by studying the interaction of a positive muon with the TCNQ nitrogen atoms. We show that both a positive muon and muonium are able to add to the nitrogen, leading to a singlet spin state for the addition molecule. This produces a characteristic three line QLCR spectrum, with the observed line positions and intensities determined by the principal values and orientation of the electric field gradient tensor at the nitrogen. Ab initio calculation of this field gradient and the resulting QLCR spectrum give good agreement with the experiment. A nonresonant background contribution to the relaxation rate also provides evidence for spin excitations rapidly diffusing along the TCNQ chains. These reflect mobile unpaired electrons introduced by muonium addition. It is thus shown that a single set of muon measurements can be sensitive to both spin and charge degrees of freedom in the same molecular material.

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Section: ■ Experimental Resultsmentioning

confidence: 99%