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Symbols, Terminology, and Nomenclature
Published in W. M. Haynes, David R. Lide, Thomas J. Bruno, CRC Handbook of Chemistry and Physics, 2016
W. M. Haynes, David R. Lide, Thomas J. Bruno
Bu bu BVE Bz Bzl C °C C c c c0 CA ca. CAB CADD cal calc cAMP CAN CAR CARS CAS CASRN CAT CBE CBS CC cc CCD CD cd CDAA CDNO CDP CDT CDTA CDW CED CEM CEP CEPA cf. CFC cfm CFRP cgs Chaps Ches CHF Chl Cho CHT Ci CI CID CIDEP butyl bushel butyl vinyl ether benzoyl benzyl coulomb; cysteine; cytosine (in genetic code) degree Celsius capacitance; heat capacity; number concentration centi (SI prefix for 10-2); combustion reaction amount concentration; specific heat; velocity speed of light in vacuum collisional activation; cellulose acetate approximately cellulose acetate butyrate computer-assisted drug design calorie calculated adenosine cyclic 3',5'-(hydrogen phosphate) ceric ammonium nitrate carbon fiber coherent anti-Stokes Raman spectroscopy complete active space Chemical Abstracts Service Registry Number computerized axial tomography; clear air turbulence chemical beam epitaxy complete basis set (of orbitals) coupled cluster; combustion calorimetry cubic centimeter charge-coupled device circular dichroism candela; condensed (phase) 2-chloro-N,N-diallylacetamide complete neglect of differential overlap cytidine 5'-diphosphate 1,5,9-cyclododecatriene (1,2-cyclohexylenedinitrilo)tetraacetic acid monohydrate charge density waves cohesive energy density channel electron multiplier counter electrophoresis coupled electron-pair approximation compare chlorofluorocarbon compound cubic feet per minute carbon reinforced plastics centimeter-gram-second system 3-[3-(cholamidopropyl)dimethylammonio]-1propanesulfonic acid 2-(N-cyclohexylamino)ethanesulfonic acid coupled Hartree-Fock (method) chlorophyll choline 1,3,5-cycloheptatriene curie configuration interaction; chemical ionization; color index charge-injection device; collision-induced dissociation chemically induced dynamic electron polarization CIDNP CIE cir CKFF CL CLT cm c.m. CMC c.m.c. CMO CMP CN CNDO Co COC COD conc const COOP cos cosh COSY COT cot coth CP Cp Cp* cP cp CPA CPC cpd CPE CPL CPR cps CPT CPU CPVC CR cr, cryst CRF CRU CSA csc CSR CT ct CTA CTEM CTFE CTP CTR cu
Application of commercially available fluorophores as triplet spin probes in EPR spectroscopy
Published in Molecular Physics, 2019
Kerstin Serrer, Clemens Matt, Monja Sokolov, Sylwia Kacprzak, Erik Schleicher, Stefan Weber
Molecular triplet states also have other very remarkable properties, such as the initial population of their three spin states far away from that at thermal equilibrium. They are generated in a state called electron–spin polarisation [7], that makes them very interesting for application in magnetic resonance [8], as, due to the low transition frequencies compared to those of optical spectroscopies, magnetic resonance is rather insensitive. This non-Boltzmann population of the triplet-state sublevels arises from symmetry-selective intersystem crossing from the corresponding excited singlet state (total spin quantum number S = 0) to the triplet (S = 1). If this peculiarity is combined with intrinsically rather insensitive techniques, high net magnetizations may be achieved, which in turn tremendously boost the sensitivity of detection, both in electron paramagnetic resonance (EPR) and nuclear magnetic resonance (NMR). Although this concept has not yet been very widely used, a few methods are now well established and exhibit, in combination with molecular triplet states, their potential for specific purposes: For example, by photo-CIDNP effects, initiated by light-generated triplet-state photochemistry, NMR resonances are enhanced [9,10]. Hyperfine couplings of the electron spin to nearby magnetic nuclei are the decisive parameters modulating the signal amplitude and sign in the liquid state. By a proper analysis of the anomalous NMR intensities, the electronic structure, as reflected by the hyperfine pattern of the investigated radical, is characterised. This allows probing paramagnetic intermediate states [11–14] that in many cases escape other means of detection, for example by EPR.
Same spectral signature in liquid-state and solid-state 1H photo-CIDNP NMR spectra of cyclohexanone
Published in Molecular Physics, 2019
Mikhail Panov, Pavlo Bielytskyi, Daniel Gräsing, Alexandra Yurkovskaya, Jörg Matysik
Photo-chemically induced dynamic nuclear polarisation (photo-CIDNP) occurs in NMR spectroscopy as hyperpolarisation of diamagnetic radical-pair reaction products [1]. This phenomenon occurs in gases [2], liquids [3] and solids [4]. In gases and liquids, photo-CIDNP is explained by the radical-pair mechanism [5]. More recently, concepts of level-crossings and anti-crossings are applied [6,7] to rationalise liquid-state photo-CIDNP. Typical systems for photo-CIDNP in the liquid-state are cyclic ketones, photooxidation of different quenchers (various amino acids, aliphatic amines) by reactive triplet states of dyes (benzophenone and flavin derivatives, 2,2′-dipyridyl) [3,8].