The rotational angular momentum orientation and alignment of the NO fragments generated via linearly polarized 308 nm photodissociation of NO2 has been determined using laser induced fluorescence. By observing the dependence of the photofragment NO Doppler-resolved transition line shapes on experimental geometry, it has proved possible to determine multipole moments of the photofragment angular momentum distribution up to, and including, rank 3. The implications of the results for the mechanism of the dissociation are considered.
OH(OD) quantum state populations, rovibrational quantum state-resolved center-of-mass angular scattering distributions, and H2(HD) coproduct internal energy release distributions have been determined for the hot H atom reactions with H2O and D2O at mean collision energies close to 1.4 eV. The experiments employ pulsed laser photolysis coupled with polarized Doppler-resolved laser induced fluorescence detection of the radical products. The OH(2Π1/2,v′=0,N′=1,A′) and OD(2Π1/2,v′=0,N′=1,A′) angular distributions generated by the two isotopic reactions are quite distinct: that for the reaction with H2O shows intensity over a wide range of center-of-mass scattering angles, and peaks in the sideways direction, while the state-resolved angular distribution for the reaction with D2O displays more scattering in the backward hemisphere. For higher OH(OD) angular momentum states the differences in the angular distributions for the two reactions are less marked, with both systems showing a slight preference for backward scattering. The kinetic energy release distributions are insensitive to OH(OD) quantum state and to isotopic substitution, and reveal that the H2(HD) coproducts are born internally cold at 1.4 eV. OH(OD) quantum state averaged energy disposals in the two reactions are also presented. The new experiments provide detailed mechanistic information about the two reactions and clarify the dominant sources of product OH(OD) rotational excitation. Current theoretical understanding of the reaction is critically assessed.
The OH state-resolved angular momentum polarization generated by the H+N2O reaction has been investigated at a mean collision energy of 1.5 eV. The data were obtained under room temperature bulb conditions using 225 nm photolysis of H2S to generate translationally excited H atoms, and employed Doppler-resolved laser induced fluorescence to probe the nascent OH reaction products. The measurements revealed the OH rotational angular momentum, j′, to be aligned in the scattering plane (i.e., in the plane containing the reactant and product relative velocity vectors, k and k′). Furthermore, j′ was found to be preferentially aligned parallel to k′, particularly for lower OH rotational states. Out-of-plane torsional forces have been shown, therefore, to play an important role in generating OH rotation as the fragments separate. The new data are discussed in light of previously published studies of the title reaction, both from our own laboratory, and from those of other workers. Insight into the reaction mechanism is provided by comparison with the photodissociation dynamics of HN3, which helps, in particular, to clarify the origin of the propeller-like OH rotational angular momentum polarization.
IntroductionThe Independent Review of the Mental Health Act (MHA) in England and Wales confirmed increasing levels of compulsory detentions, especially for racialised communities. This research aims to: (a) understand the causes of and propose preventive opportunities to reduce the disproportionate use of the MHA, (b) use an adapted form of experience-based codesign (EBCD) to facilitate system-wide changes and (c) foreground the voices of service users at risk of detention to radically reform policy and implement new legislation to ensure the principles of equity are retained.Methods and analysisThis is a qualitative study, using a comparative case study design. This study is composed of five work packages; photovoice workshops will be conducted in eight local systems with service users and healthcare professionals separately (WP1); a series of three EBCD workshops in each local system to develop approaches that reduce detentions and improve the experience of people from racialised communities. This will inform a comparative analysis and national knowledge exchange workshop (WP2); an evaluation led by the patient and public involvement group to better understand what it is like for people to participate in photovoice, codesign and participatory research (WP3); an economic evaluation (WP4) and dissemination strategy (WP5). The impact of the involvement of patients and public will be independently evaluated.Ethics and disseminationThis study is sponsored by the University of Oxford and granted ethical approval from the NHS Research Ethics Committee and Health Research Authority (21/SC/0204). The outputs from this study will be shared through several local and national channels.
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