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1. Development and status of MAPS, the MMT AO exoPlanet characterization system

   https://doi.org/10.1117/12.2563178  

   Morzinski, Katie M.; Montoya, Manny; Fellows, Chuck; Durney, Olivier; Ford, John; West, Grant; Gardner, Andrew; Vaz, Amali; Anugu, Narsireddy; Mailhot, Emily; et al (December 2020, Proceedings of the SPIE)

   Schmidt, Dirk; Schreiber, Laura; Vernet, Elise (Ed.)

   We are upgrading and refurbishing the first-generation adaptive-secondary mirror (ASM)-based AO system on the 6.5-m MMT in Arizona, in an NSF MSIP-funded program that will create a unique facility specialized for exoplanet characterization. This update includes a third-generation ASM with embedded electronics for low power consumption, two pyramid wavefront sensors (optical and near-IR), and an upgraded ARIES science camera for high-resolution spectroscopy (HRS) from 1-5 μm and MMT-POL science camera for sensitive polarization mapping. Digital electronics have been incorporated into each of the 336 actuators, simplifying hub-level electronics and reducing the total power to 300 W, down from 1800 W in the legacy system — reducing cooling requirements from active coolant to passive ambient cooling. An improved internal control law allows for electronic damping and a faster response. The dual pyramid wavefront sensors allow for a choice between optical or IR wavefront sensing depending on guide star magnitude, color, and extinction. The HRS upgrade to ARIES enables crosscorrelation of molecular templates to extract atmospheric parameters of exoplanets. The combination of these upgrades creates a workhorse instrument for exoplanet characterization via AO and HRS to separate planets from their host stars, with broad wavelength coverage and polarization to probe a range of molecular species in exoplanet atmospheres. 

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2. Role of Intercalation on Electrical Properties of Nucleic Acids for use in Molecular Electronics

   https://doi.org/10.1039/D1NH00211B  

   Mohammad, Hashem; Demir, Busra; Akin, Caglanaz; Luan, Binquan; Hihath, Joshua; Oren, Ersin Emre; Anantram, M. P. (January 2021, Nanoscale Horizons)

   null (Ed.)

   Intercalating ds-DNA/RNA with small molecules can play an essential role in controlling the electron transmission probability for molecular electronics applications such as biosensors, single-molecule transistors, and data storage. However, its applications are limited due to a lack of understanding the nature of intercalation and electron transport mechanisms. We addressed this long-standing problem by studying the effect of intercalation on both the molecular structure and charge transport along the nucleic acids using molecular dynamics simulations and first-principle calculations coupled with Green’s function method, respectively. The study on anthraquinone and anthraquinone-neomycin conjugate intercalation into short nucleic acids reveals some universal features: 1) the intercalation affects the transmission by two mechanisms: a) inducing energy levels within the bandgap and b) shifting the location of the Fermi energy with respect to the molecular orbitals of the nucleic acid, 2) the effect of intercalation was found to be dependent on the redox state of the intercalator: while oxidized anthraquinone decreases, reduced anthraquinone increases the conductance, and 3) the sequence of intercalated nucleic acid further affects the transmission: lowering the AT-region length was found to enhance the electronic coupling of the intercalator with GC bases, hence yielding an increase of more than four times in conductance. We anticipate our study to inspire designing intercalator-nucleic acid complexes for potential use in molecular electronics via creating a multi-level gating effect. 

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3. Ultraviolet Hyperspectral Interferometric Microscopy

   https://doi.org/10.1038/s41598-018-28208-0  

   Ojaghi, Ashkan; Fay, Meredith E.; Lam, Wilbur A.; Robles, Francisco E. (July 2018, Scientific Reports)

   Abstract Ultraviolet (UV) spectroscopy is a powerful tool for quantitative (bio)chemical analysis, but its application to molecular imaging and microscopy has been limited. Here we introduce ultraviolet hyperspectral interferometric (UHI) microscopy, which leverages coherent detection of optical fields to overcome significant challenges associated with UV spectroscopy when applied to molecular imaging. We demonstrate that this method enables quantitative spectral analysis of important endogenous biomolecules with subcellular spatial resolution and sensitivity to nanometer-scaled structures for label-free molecular imaging of live cells. 

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4. Broadband cavity-enhanced ultrafast spectroscopy

   https://doi.org/10.1039/D1CP00631B  

   Silfies, Myles C.; Kowzan, Grzegorz; Lewis, Neomi; Allison, Thomas K. (April 2021, Physical Chemistry Chemical Physics)

   null (Ed.)

   Broadband ultrafast optical spectroscopy methods, such as transient absorption spectroscopy and 2D spectroscopy, are widely used to study molecular dynamics. However, these techniques are typically restricted to optically thick samples, such as solids and liquid solutions. In this article we discuss a cavity-enhanced ultrafast transient absorption spectrometer covering almost the entire visible range with a detection limit of ΔOD < 1 × 10 −9 , extending broadband all-optical ultrafast spectroscopy techniques to dilute beams of gas-phase molecules and clusters. We describe the technical innovations behind the spectrometer and present transient absorption data on two archetypical molecular systems for excited-state intramolecular proton transfer, 1′-hydroxy-2′-acetonapthone and salicylideneaniline, under jet-cooled and Ar cluster conditions. 

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5. Computational investigation of structural, electronic, and spectroscopic properties of Ni and Zn metalloporphyrins with varying anchoring groups

   https://doi.org/10.1063/5.0191858  

   Bashir, Beenish; Alotaibi, Maha_M; Clayborne, Andre_Z (April 2024, The Journal of Chemical Physics)

   Porphyrins are prime candidates for a host of molecular electronics applications. Understanding the electronic structure and the role of anchoring groups on porphyrins is a prerequisite for researchers to comprehend their role in molecular devices at the molecular junction interface. Here, we use the density functional theory approach to investigate the influence of anchoring groups on Ni and Zn diphenylporphyrin molecules. The changes in geometry, electronic structure, and electronic descriptors were evaluated. There are minimal changes observed in geometry when changing the metal from Ni to Zn and the anchoring group. However, we find that the distribution of electron density changes when changing the anchoring group in the highest occupied and lowest unoccupied molecular orbitals. This has a direct effect on electronic descriptors such as global hardness, softness, and electrophilicity. Additionally, the optical spectra of both Ni and Zn diphenylporphyrin molecules exhibit either blue or red shifts when changing the anchoring group. These results indicate the importance of the anchoring group on the electronic structure and optical properties of porphyrin molecules. 

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