Particle metal interactions - a raman and electrochemical study of a compacted electrode of copper phthalocyanine and silver metal

Electrodes consisting of a compacted mixture of powders of silver metal and copper phthalocyanine (CuPc) have been used to study the interaction between small pigment particles and a metal surface using resonance Raman spectroscopy as a probe of in situ changes. The purpose of this present paper is to explore the condition required to produce optimum enhancement.Cycling in acid sulphate or nitrate electrolytes with a sufficiently positive voltage to release silver(I) ions resulted in the formation of a thin layer of CuPc particles spread out on the metal surface. The layer formed produced an improvement in Raman scattering from CuPc. From the resonance profile it was clear that there was a significant charge transfer interaction with the metal surface. The relative intensities of the peaks in the Raman spectra are dependent on potential. As well as the possible use of such electrodes in chemistry, particle metal layers of this type provide a different starting point for studies of the surface enhanced resonance Raman effect emphasising the electromagnetic contribution rather than the chemical one

Nature of the improved raman-scattering from alpha-copper phthalocyanine particles on a compacted electrode

Electrodes consisting of a compacted mixture of powders of silver metal and alpha-copper phthalocyanine (CuPc) have been used to study small pigment particles bonded to the metal surface using resonance Raman spectroscopy as a probe of in situ changes. This system provides a different starting point for the study of the nature of the terms which give rise to improved Raman scattering at metal surfaces. An understanding of these processes is vital if Raman spectroscopy is to achieve its potential as an in situ method for the detection of reactions at metal/organic interfaces in aqueous solution. Resonance excitation profiles (REPs) indicate that the improved scattering is in the region of the phthalocyanine absorption (Q band) and resembles a CuPc multilayer. There is a significant electronic interaction between the particles and the metal surface with a downward shift in the O-O transition energy of the Q band of ca. 30 nm. The REPs from the electrode surface are more clearly resolved than for CuPc itself. There are fewer effective vibronic contributions especially at negative potentials and scattering is greater from higher vibronic levels. New bands not present in the spectrum of CuPc appear at negative potentials and the appearance coincides with changes in intensity of bands observed at all potentials. Two different mechanisms of enhancement are indicated: a resonance mechanism where increased scattering efficiency is achieved both by good sample presentation and by an electronic interaction between the particles and the metal, and a surface-enhanced resonance effect which competes with the resonance mechanism at negative potentials. Both the resonance effect and the surface-enhanced effect give rise to REPs attributable to phthalocyanine Q-band interactions. Both processes arise from a long-range 'charge-transfer' mechanisms between the CuPc particles and the metal rather than from short-range metal-monolayer interactions

Resonance raman-spectra of alpha-copper phthalocyanine

This paper discusses the resonance raman-spectra of alpha-copper phthalocyanine

Raman-scattering of alpha-copper phthalocyanine and other complexes formed at a silver surface using a compacted electrode

A novel compacted electrode technique is used to obtain a layer of the insoluble pigment α-copper phthalocyanine on a silver surface. Electrochemical treatment improves the signal to noise ratio of the Raman spectrum of the phthalocyanine at the surface and a selective enhancement of some bands indicates a SERS effect as well as resonance. Silver phthalocyanine can be synthesised at a silver surface using compacted electrodes of silver and either metal-free phthalocyanine or o-phthalonitrile. The formation of the layer of complex at the surface can be observed by Raman spectroscopy. The method was extended to a non-phthalocyanine system using a silver/bipyridyl compacted electrode, which gave a detectable layer of a silver bipyridyl complex at the electrode surface and a solution of a soluble silver bipyridyl complex. This combination of a compacted electrode and Raman spectroscopy appears ideal for the synthesis and characterization of a range of transition-metal complex/metal surfaces

Overtone and combination band raman-spectra of alpha-copper phthalocyanine

Compacted electrodes made by pressing alpha-copper phthalocyanine (alpha-CuPc) and silver metal powder provide an effective method to measure resonance Raman scattering from alpha-CuPc. We report first and very weak second overtone and combination bands of alpha-CuPc. They are based on progressions in nu(3), nu(4), nu(7) and nu(15) modes. Three of these are A1g vibrations of alpha-CuPc, indicating a much stronger symmetric contribution to overtone scattering than is the case in porphyrins. Overtone profiles at 0 V vs. SCE arise mainly from scattering from 0 to 1 vibronic overtone states with evidence of higher state contributions in some cases. This is in contrast to the more varied profiles of fundamental modes and is as expected from theory. The results support the view that Raman scattering from alpha-CuPc involves a Jahn-Teller distorted excited state and is due to A as well as B term enhancement

Crowdsourcing: A novel tool to elicit the student voice in the curriculum design process for an undergraduate diagnostic radiography degree programme

Introduction: Stakeholder participation in healthcare curriculum design is an important aspect of higher education with stakeholders including students, staff members, clinical partners, healthcare organisations, patients and members of the public. Significantly, student co-creation, of the curriculum, has become increasingly important. Yet there is limited research which addresses how to engage this group in design processes. Methods: This paper represents the first phase of a three stage action research spiral whereby the authors evaluated the use of a novel tool for curriculum design processes, anonymised crowdsourcing. This initial phase was open to all students enrolled on an undergraduate diagnostic radiography programme in the UK. To confirm the reliability of the crowdsource design an established eight point crowdsourcing verification tool was applied. Results: Twenty-three unique ideas were generated by participants, 40 comments made and 173 votes cast. Inductive analysis of the comments generated five themes. These included: the role of technology enhanced learning; simulation activities; patient focused curriculum; mental wealth (resilience) authentic assessment approaches. An evaluation of those who had and had not engaged highlighted areas of improvement for the administration of the second and third iterations which will include a wider pool of participants. Conclusion: This study from a single programme offers lessons for others wishing to adopt and develop this approach elsewhere. Implications for practice: Several ideas elicited by the crowdsource have been considered by the curriculum design team and will be implemented in the 2020 curriculum thus demonstrating the impact on local education practice of this research approach