Strong Coupling of Molecular Vibrational Resonances

Strong coupling of molecules placed in an optical microcavity may lead to the formation of hybrid states called polaritons; states that inherit characteristics of both the optical cavity modes and the molecular resonance. This is possible for both excitonic and vibrational molecular resonances. Previous work has shown that strong coupling may be used to hybridize different excitonic resonances, this can be achieved when more than one molecular species is included in the cavity. In this thesis I show that under suitable conditions different molecular vibrational resonances of the same molecular unit may also be coupled together, the resulting polariton having characteristics of all vibrational resonances. I will also demonstrate strong coupling between surface plasmon resonances and molecular vibrational resonances of polymethylmethacrylate (PMMA) molecules in the mid-infrared range through the use of grating coupling, complimenting earlier work using microcavities and localised plasmon resonances. Many experiments involving strong coupling make use of metal-clad microcavities, ones with metallic mirrors. Metal-clad microcavities are well known to support coupled plasmon modes in addition to the standard microcavity mode. However, the coupled plasmon modes associated with an optical microcavity lie beyond the light-line and are thus not probed in typical experiments on strong coupling. I will investigate, through experiment and numerical modelling, the interaction between molecules within a cavity and the coupled plasmon mode and I will show that such modes do undergo strong coupling, making use of grating coupling to provide an experimental demonstration. Overall, light−matter hybridization offers many new opportunities for the molecular and materials sciences. It works in the absence of light, it is simple to implement, and its full potential is waiting to be explored.Engineering and Physical Sciences Research Council (EPSRC

Hybridization of multiple vibrational modes via strong coupling using confined light fields (article)

This is the final version. Available on open access from Wiley via the DOI in this record.Data associated with this paper can be found at https://doi.org/10.24378/exe.1403Strong coupling of molecules placed in an optical microcavity may lead to the formation of hybrid states called polaritons; states that inherit characteristics of both the optical cavity modes and the molecular resonance. This is possible for both excitonic and vibrational molecular resonances. Previous work has shown that strong coupling may be used to hybridize two different excitonic resonances, this can be achieved when more than one molecular species is included in the cavity. Here we show that under suitable conditions three different molecular vibrational resonances of the same molecular unit may also be coupled together, the resulting polariton having characteristics of all three vibrational resonances. Our results lead us to suggest that strong coupling might be used to manipulate vibrational resonances in a richer and subtler way than previously considered, opening a path to greater control of molecular systems and molecular processes via vibrational strong coupling.Engineering and Physical Sciences Research Council (EPSRC)European Research Counci

Swiss adolescents' and adults' perceptions of cannabis use: a qualitative study

Few studies have attempted to investigate the nature of adolescents' and adults' conceptions and perceptions of cannabis use. Our objectives were to explore adolescent and adult perception of use and misuse of cannabis, and their opinions and beliefs about the current legal context and preventive strategies. We used focus group discussions with four categories of stakeholders: younger (12-15 year old) adolescents, older (16-19 year old) adolescents, parents of teenagers and professionals working with young people. In some areas (legal framework, role of the media, importance of early preventive interventions), we found consensual attitudes and beliefs across the four groups of participants. In all four groups, participants did not have any consensual vision of the risks of cannabis use or the definition of misuse. In the area of the prevention of cannabis use/misuse, while parents focused on the potential role of professionals and the media, thus minimizing their own educational and preventive role, professionals stressed the importance of parental control and education. Within the Swiss context, we conclude there exists an urgent need for information and clarification of the issues linked with cannabis use and misuse directed at parents and professional

Swiss adolescents' and adults' perceptions of cannabis use: a qualitative study.

Few studies have attempted to investigate the nature of adolescents' and adults' conceptions and perceptions of cannabis use. Our objectives were to explore adolescent and adult perception of use and misuse of cannabis, and their opinions and beliefs about the current legal context and preventive strategies. We used focus group discussions with four categories of stakeholders: younger (12-15 year old) adolescents, older (16-19 year old) adolescents, parents of teenagers and professionals working with young people. In some areas (legal framework, role of the media, importance of early preventive interventions), we found consensual attitudes and beliefs across the four groups of participants. In all four groups, participants did not have any consensual vision of the risks of cannabis use or the definition of misuse. In the area of the prevention of cannabis use/misuse, while parents focused on the potential role of professionals and the media, thus minimizing their own educational and preventive role, professionals stressed the importance of parental control and education. Within the Swiss context, we conclude there exists an urgent need for information and clarification of the issues linked with cannabis use and misuse directed at parents and professionals

Risk classification at diagnosis predicts post-HCT outcomes in intermediate-, adverse-risk, and KMT2A-rearranged AML

Little is known about whether risk classification at diagnosis predicts post-hematopoietic cell transplantation (HCT) outcomes in patients with acute myeloid leukemia (AML). We evaluated 8709 patients with AML from the CIBMTR database, and after selection and manual curation of the cytogenetics data, 3779 patients in first complete remission were included in the final analysis: 2384 with intermediate-risk, 969 with adverse-risk, and 426 with KMT2A-rearranged disease. An adjusted multivariable analysis detected an increased risk of relapse for patients with KMT2A-rearranged or adverse-risk AML as compared to those with intermediate-risk disease (hazards ratio [HR], 1.27; P 5.01; HR, 1.71; P,.001, respectively). Leukemia-free survival was similar for patients with KMT2A rearrangement or adverse risk (HR, 1.26; P 5.002, and HR, 1.47; P,.001), as was overall survival (HR, 1.32; P,.001, and HR, 1.45; P,.001). No differences in outcome were detected when patients were stratified by KMT2A fusion partner. This study is the largest conducted to date on post-HCT outcomes in AML, with manually curated cytogenetics used for risk stratification. Our work demonstrates that risk classification at diagnosis remains predictive of post-HCT outcomes in AML. It also highlights the critical need to develop novel treatment strategies for patients with KMT2A-rearranged and adverse-risk disease

Implications of TP53 allelic state for genome stability, clinical presentation and outcomes in myelodysplastic syndromes

Tumor protein p53 (TP53) is the most frequently mutated gene in cancer1,2. In patients with myelodysplastic syndromes (MDS), TP53 mutations are associated with high-risk disease3,4, rapid transformation to acute myeloid leukemia (AML)5, resistance to conventional therapies6–8 and dismal outcomes9. Consistent with the tumor-suppressive role of TP53, patients harbor both mono- and biallelic mutations10. However, the biological and clinical implications of TP53 allelic state have not been fully investigated in MDS or any other cancer type. We analyzed 3,324 patients with MDS for TP53 mutations and allelic imbalances and delineated two subsets of patients with distinct phenotypes and outcomes. One-third of TP53-mutated patients had monoallelic mutations whereas two-thirds had multiple hits (multi-hit) consistent with biallelic targeting. Established associations with complex karyotype, few co-occurring mutations, high-risk presentation and poor outcomes were specific to multi-hit patients only. TP53 multi-hit state predicted risk of death and leukemic transformation independently of the Revised International Prognostic Scoring System (IPSS-R)11. Surprisingly, monoallelic patients did not differ from TP53 wild-type patients in outcomes and response to therapy. This study shows that consideration of TP53 allelic state is critical for diagnostic and prognostic precision in MDS as well as in future correlative studies of treatment response

Strong coupling beyond the light-line (dataset)

Data used to produce the figures in the Menghrajani and Barnes (2020) article "Strong coupling beyond the light-line" published in ACS Photonics. Strong coupling of molecules placed in an optical microcavity may lead to the formation of hybrid states called polaritons; states that inherit characteristics of both the optical cav- ity modes and the molecular resonance. Developing a better understanding of the matter characteristics of these hybrid states has been the focus of much recent attention. Here, as we will show, a better understanding of the role of the optical modes supported by typical cavity structures is also required. Typical microcavities used in molecular strong coupling experiments support more than one mode at the frequency of the material resonance, but previous work has almost exclusively considered only one of these modes. Many experiments involving strong coupling make use of metal-clad microcavities, ones with metallic mirrors. Metal-clad microcavities are well known to support coupled plasmon modes in addition to the standard microcavity mode. However, the coupled plasmon modes associated with a metal-clad optical microcavity lie beyond the light-line and are thus not probed in typical experiments on strong coupling. Here we investigate, through experiment and numerical modelling, the interaction between molecules within a cavity and the modes both inside and outside the light-line. Making use of grating coupling and a metal-clad microcavity we pro- vide an experimental demonstration that such modes undergo strong coupling. We further show that a common variant of the metal-clad microcavity, one in which the metal mirrors are replaced by distributed Bragg reflector also show strong coupling to modes that exist in these structures beyond the light-line. Our results highlight the need to consider the effect of beyond the light-line modes on the strong coupling of molecular resonances in microcavities, and may be of relevance in designing strong coupling resonators for chemistry and materials science investigations.Engineering and Physical Sciences Research Council (EPSRC)European Research Counci

Probing vibrational strong coupling of molecules with Wavelength-modulated Raman spectroscopy (dataset)

This is the dataset used for the Menghranjani et al. (2021) article "Probing vibrational strong coupling of molecules with Wavelength-modulated Raman spectroscopy" published in Advanced Optical Materials.Experimentally/Computationally calculated data of all the figures.Raman spectroscopy is a powerful technique that enables fingerprinting of materials, molecules, and chemical environments by probing vibrational resonances. In many applications the desired Raman signals are masked by fluorescence, either from the molecular system being studied, or from adjacent metallic nanostructures. Here we show that wavelength-modulated Raman spectroscopy provides a powerful way to significantly reduce the strength of the fluorescence background, thereby allowing the desired Raman signals to be clearly recorded. We make use of this approach to explore Raman scattering in the context of vibrational strong coupling, an area that has thus far been problematic to visualise. Specifically we look at strong coupling between the vibrational modes in a polymer and two types of confined light field, the fundamental mode of a metal-clad microcavity, and the surface-plasmon modes of an adjacent thin metal film. Whilst we find clear advantages in using the wavelength-modulated Raman approach, our results on strong coupling are inconclusive, and highlight the need for more work in this exciting topic area.European CommissionEngineering and Physical Sciences Research Council (EPSRC

Hybridization of multiple vibrational modes via strong coupling using confined light fields (dataset)

The article associated with this dataset is located in ORE at: http://hdl.handle.net/10871/37513This is the dataset used for the Menghrajani et al. (2019) article "Hybridization of multiple vibrational modes via strong coupling using confined light fields" published in the journal of Advanced Optical Materials.Engineering and Physical Sciences Research Council (EPSRC)European Commissio

Probing vibrational strong coupling of molecules with Wavelength-modulated Raman spectroscopy (dataset)

Raman spectroscopy is a powerful technique that enables fingerprinting of materials, molecules, and chemical environments by probing vibrational resonances. In many applications the desired Raman signals are masked by fluorescence, either from the molecular system being studied, or from adjacent metallic nanostructures. Here we show that wavelength-modulated Raman spectroscopy provides a powerful way to significantly reduce the strength of the fluorescence background, thereby allowing the desired Raman signals to be clearly recorded. We make use of this approach to explore Raman scattering in the context of vibrational strong coupling, an area that has thus far been problematic to visualise. Specifically we look at strong coupling between the vibrational modes in a polymer and two types of confined light field, the fundamental mode of a metal-clad microcavity, and the surface-plasmon modes of an adjacent thin metal film. Whilst we find clear advantages in using the wavelength-modulated Raman approach, our results on strong coupling are inconclusive, and highlight the need for more work in this exciting topic area.,This is the dataset used for the Menghranjani et al. (2021) article "Probing vibrational strong coupling of molecules with Wavelength-modulated Raman spectroscopy" published in Advanced Optical Materials.,Experimentally/Computationally calculated data of all the figures.