On the observation of photo-excitation effects in molecules using muon spin spectroscopy.
About: This article is published in Nature Materials.The article was published on 2021-05-10. It has received 1 citations till now. The article focuses on the topics: Muon spin spectroscopy.
Citations
More filters
References
More filters
01 Jan 1988
TL;DR: In this paper, the authors used the muon as a probe in matter and observed the formation of free radicals in a single crystal and the evolution of spin polarization in the liquid phase.
Abstract: 1 Introduction.- 1.1 Motivation.- 1.2 History and properties of the muon and its bound states.- 1.3 The muon as a probe in matter.- 1.3.1 Principle of the experiment.- 1.3.2 Solid state physics.- 1.3.3 Chemistry.- 2 Experiments employing muons.- 2.1 Muon production and decay.- 2.2 The ?SR techniques.- 2.2.1 Time differential transverse field ?SR.- 2.2.2 Time integrated longitudinal field ?SR.- 2.2.3 Other techniques.- 2.3 Analysis and interpretation of the data.- 3 Theory.- 3.1 Hamiltonians, eigenvectors and energies.- 3.1.1 Muons in diamagnetic environments.- 3.1.2 Muonium.- 3.1.3 Muonated free radicals.- 3.2 Evolution of spin polarization.- 3.2.1 Evaluation for a general species formed at time zero.- 3.2.2 Evaluation for a slowly formed radical.- 3.2.3 Evaluation for a slowly formed diamagnetic species.- 4 The cyclohexadienyl radical.- 4.1 Observation in the liquid phase.- 4.1.1 Transverse fiel?SR.- 4.1.2 Avoided level crossing ?SR.- 4.2 Observation in other phases.- 4.2.1 The first experiment with a single crystal.- 4.2.2 Observation of a surface adsorbed radical.- 4.3 Structure and hyperfine couplings.- 4.3.1 Structure of cyclohexadienyl and benzyl.- 4.3.2 Wave functions and hyperfine coupling constants.- 4.3.3 Isotope effects.- 5 Substituent effects on hyperfine coupling constants.- 5.1 Monosubstituted radicals.- 5.2 Comparison with data for benzyl.- 5.3 Polysubstituted radicals.- 5.3.1 Experimental observations.- 5.3.2 Do coupling constants reflect capto-dative stabilization?.- 6 The process of radical formation.- 6.1 Routes to the cyclohexadienyl radical.- 6.2 Radical formation in cyclohexane solution.- 6.3 Selectivity in mixtures of benzene and dimethylbutadiene.- 6.4 Scavenging experiments.- 6.4.1 The effect of carbon tetrachloride.- 6.4.2 The effect of methyliodide.- 6.4.3 The effect of iodine.- 7 Distribution of muons in substituted benzenes.- 7.1 Monosubstituted benzenes.- 7.1.1 End-of-track effects on the muon distribution between radicals and diamagnetic species.- 7.1.2 Regioselectivity in the formation of radicals.- 7.1.3 Relative rate constants and partial rate factors for Mu addition.- 7.2 Polysubstituted benzenes.- 8 Radical reactions.- 8.1 Secondary isotope effects.- 8.2 Electron transfer reactions.- 8.3 Abstraction reactions.- 8.4 Spin exchange reactions.- 8.5 Transfer of bound Mu, an example for a primary kinetic isotope effect.- 9 Summary and review.- 9.1 Objective.- 9.2 The requirements for the observation of muonated radicals.- 9.3 The different types of radicals observed in liquids.- 9.4 Observations in other phases.- 9.5 Investigation of isotope effects.- 9.6 Investigation of early events.- 9.7 Investigation of radical kinetics.- 9.8 Conclusion.
148 citations
TL;DR: The high magnetic field (HiFi) muon instrument at the ISIS pulsed neutron and muon source is a state-of-the-art spectrometer designed to provide applied magnetic fields up to 5 T for muon studies of condensed matter and molecular systems.
Abstract: The high magnetic field (HiFi) muon instrument at the ISIS pulsed neutron and muon source is a state-of-the-art spectrometer designed to provide applied magnetic fields up to 5 T for muon studies of condensed matter and molecular systems. The spectrometer is optimised for time-differential muon spin relaxation studies at a pulsed muon source. We describe the challenges involved in its design and construction, detailing, in particular, the magnet and detector performance. Commissioning experiments have been conducted and the results are presented to demonstrate the scientific capabilities of the new instrument.
33 citations
TL;DR: It is demonstrated that laser-excited muon pump-probe spin spectroscopy (photo-μSR) can temporally and spatially map photochemical processes with a spatial resolution at the single-carbon level in a molecule with a pentacene backbone.
Abstract: Photochemical reactions are essential to a large number of important industrial and biological processes. A method for monitoring photochemical reaction kinetics and the dynamics of molecular excitations with spatial resolution within the active molecule would allow a rigorous exploration of the pathway and mechanism of photophysical and photochemical processes. Here we demonstrate that laser-excited muon pump-probe spin spectroscopy (photo-μSR) can temporally and spatially map these processes with a spatial resolution at the single-carbon level in a molecule with a pentacene backbone. The observed time-dependent light-induced changes of an avoided level crossing resonance demonstrate that the photochemical reactivity of a specific carbon atom is modified as a result of the presence of the excited state wavefunction. This demonstrates the sensitivity and potential of this technique in probing molecular excitations and photochemistry.
15 citations