The VSFG spectra of PTAA in the vicinity of 1600 cm -1 were modeled using a simplified expression for the effective second order susceptibility χ eff (2) which includes a single vibrational resonance while summing all other possible contributions into an additional susceptibility term used generally to model the slowly varying voltage-dependent VSFG background. Apart from the discrete vibrationally resonant contributions, the broad background response observed in the VSFG spectra of charge bearing PTAA thin films has potential contributions due to electronically resonant (polaron), nonresonant, and

This article describes an ongoing initiative of the Department of Chemistry (Chem. Dept.) at the University of Minnesota (UMN) to support the mental health of graduate students. With the increasing pressure on students to carry out novel research, publish articles, learn a broad range of skills, and look for career opportunities, the levels of stress, anxiety, and depression among graduate students are on the rise. For tackling these issues, the UMN Chem. Dept. has adopted an approach that heavily relies on the involvement of graduate students and student empowerment. This contribution describes the results of a collaboration between a student group (Community of Chemistry Graduate Students, CCGS), the director of graduate studies of the Chem. Dept., and mental health professionals at the UMN campus health service, to provide strategies for ensuring a welcoming and productive departmental climate. It describes the events that CCGS has hosted to help to improve the mental health of students, and raise awareness and stimulate open discussions about this topic. As an early intervention strategy, the UMN Chem. Dept. revised several policies to ensure that students receive frequent feedback from their advisors. Through the collaboration of the CCGS, UMN Chem. Dept., and UMN campus health service, a survey for the evaluation of mental health and stress factors in graduate studies was developed. Findings of the survey attest to the stigma associated with mental health, as more than 40% of the graduate students responded that they did not consider consulting with a therapist, counselor, or physician even when they felt that their health was affected by the level of stress in their lives. The results also show the importance of an open and friendly environment for students who struggle with stress and mental health, as they were most likely to approach a friend rather than advisor, counselor, or physician.

Vibrational sum frequency generation (VSFG) spectroscopy was used to measure the interfacial spectra of fullerene thin films on dielectric substrates that are commonly used in IR spectroscopy. The VSFG spectra on SiO2 and CaF2 exhibit notably different intensities for the F1u and Ag vibrational modes. This difference is attributed to different interfacial surface charges and C60/surface interactions. DFT calculations were performed to model the influence of a unidirectional electrostatic perturbation on the IR and Raman activities. The VSFG activities were then calculated for comparison to the interfacial second-order susceptibilities obtained from multilayer interference fitting of the experimental spectra. We find that the negative surface charge of CaF2 substrates causes a larger perturbation of fullerene than native silica surfaces, which leads to a stronger influence on the VSFG spectra.

The crowding effect is prevalent in cellular environments due to high concentrations of biomacromolecules. It can alter the structures and dynamics of proteins and thus impact protein functions. The crowding effect is important not only in 3-dimensional cytoplasm but also for a 2-dimensional (2D) cell surface due to the presence of membrane proteins and glycosylation of membrane proteins and phospholipids. These proteins and phospholipids - with limited translational degrees of freedom along the surface normal - are confined in 2D space. Although the crowding effect at interfaces has been studied by adding crowding agents to bulk solution, the 2D crowding effect remains largely unexplored. This is mostly due to challenges in controlling 2D crowding and synergistic use of physical methods for in situ protein characterization. To address these challenges, we applied chiral vibrational sum frequency generation (SFG) spectroscopy to probe the sp1 zinc finger (ZnF), a 31-amino acid protein, folding into a β-hairpin/α-helix (ββα) motif upon binding to Zn2+. We anchored ZnF at the air/water interface via covalent linkage of ZnF to palmitic acid and controlled 2D crowding by introducing neutral lipid as a spacer. We obtained chiral amide I SFG spectra upon addition of Zn2+ and/or spacer lipid. The chiral SFG spectra show that interfacial crowding in the absence of spacer lipid hinders ZnF from folding into the ββα structure even in the presence of Zn2+. The results establish a paradigm for future quantitative, systematic studies of interfacial crowding effects.