Visible-infrared sum-frequency spectroscopy is ideally suited to the study of surfaces and interfaces. This paper introduces new sum-frequency spectroscopy instrumentation that we have developed with two novel features: (1) stable and robust infrared generation in the 900-3100 cm(-1) (11-3.2 microm) region using an amplified Ti : sapphire oscillator with a home-built OPG/OPA, and (2) continuous tuning over either 900-2700 cm(-1) (11-3.7 microm) or 1800-3100 cm(-1) (5.5-3.2 microm) in a single experiment. All practical details of baseline correction issues due to the picosecond pulses (including variation in infrared (IR) energy, spatial and temporal overlap, Fresnel coefficients) are addressed while demonstrating signal throughout this region from an amorphous gold surface. A sum-frequency spectrum from an oriented polymer is shown as a complete example of the data treatment, which reveals the vibrational modes accessible in this wavelength region.
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http://dx.doi.org/10.1366/0003702042641344 | DOI Listing |
J Chem Phys
January 2025
Graduate School of Engineering, Chiba University, 1-33, Yayoi-cho, Inage-ku, Chiba, Chiba 263-8522, Japan.
Organic multilayer systems, which are stacked layers of different organic materials, are used in various organic electronic devices such as organic light-emitting diodes (OLEDs) and organic field-effect transistors (OFETs). In particular, OFETs are promising as key components in flexible electronic devices. In this study, we investigated how the inclusion of an insulating tetratetracontane (TTC) interlayer in ambipolar indigo-based OFETs can be used to alter the crystallinity and electrical properties of the indigo charge transport layer.
View Article and Find Full Text PDFJ Chem Phys
January 2025
Department of Chemistry, Boston University, 590 Commonwealth Avenue, Boston, Massachusetts 02215, USA.
The computational spectroscopy of water has proven to be a powerful tool for probing the structure and dynamics of chemical systems and for providing atomistic insight into experimental vibrational spectroscopic results. However, such calculations have been limited for biochemical systems due to the lack of empirical vibrational frequency maps for the TIP3P water model, which is used in many popular biomolecular force fields. Here, we develop an empirical map for the TIP3P model and evaluate its efficacy for reproducing the experimental vibrational spectroscopy of water.
View Article and Find Full Text PDFJ Chem Phys
January 2025
Department of Chemistry, University of Houston, Houston, Texas 77204, USA.
Rubrene is one of the leading organic semiconductors in scientific and industrial research, showing good conductivities and utilities in devices such as organic field-effect transistors. In these applications, the rubrene crystals often contact ionic liquids and other materials. Consequently, their surface properties and interfacial interactions influence the device's performance.
View Article and Find Full Text PDFJ Chem Phys
January 2025
Department of Materials Science and Engineering, Tokyo Institute of Technology, O-okayama, Meguro-ku, Tokyo 152-8552, Japan.
The liquid/liquid interfaces of room-temperature ionic liquids (RTILs) play a pivotal role in chemical reactions owing to their characteristic microscopic structure, yet the structure of hydrophobic liquid/RTIL interfaces remains unclear. We studied the structure at the liquid/liquid interfaces of carbon tetrachloride (CCl4) and 1-alkyl-3-methylimidazolium bis(trifluoromethanesulfonyl)amide ([Cnmim][TFSA]; n = 4 and 8) RTILs using infrared-visible sum frequency generation (SFG) vibrational spectroscopy. A comparison of the SFG spectra of the CCl4/RTIL and air/RTIL interfaces revealed that the solvation of the alkyl chains of the [Cnmim]+ cations by CCl4 reduces the number of gauche defects in the alkyl chain and the interface number density of the cation at the CCl4 interface.
View Article and Find Full Text PDFJ Am Chem Soc
January 2025
Chemical Sciences Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, United States.
Chemical selectivity is traditionally understood in the context of rigid molecular scaffolds with precisely defined local coordination and chemical environments that ultimately facilitate a given transformation of interest. By contrast, nature leverages dynamic structures and strong coupling to enable specific interactions with target species in otherwise complex media. Taking inspiration from nature, we demonstrate unconventional selectivity in the solvent extraction of light over heavy lanthanides using a conformationally flexible ligand called octadecyl acyclopa (ODA).
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