Over 2 mW of continuous-wave tunable 194-nm light is produced by sum-frequency mixing approximately 500 mW of 792-nm and 500 mW of 257-nm radiation in beta-barium borate (BBO). The powers in both fundamental beams are enhanced in separate ring cavities whose optical paths overlap in the Brewster-cut BBO crystal. Due to the higher circulating fundamental powers, the sum-frequency-generated power is nearly 2 orders of magnitude greater than previously reported values.
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http://dx.doi.org/10.1364/ao.36.004159 | DOI Listing |
Congruent lithium niobate is a type of lithium niobate crystal with a mature growth process and is widely used in nonlinear optics research. Its refractive index accuracy will play a crucial role in the research and application of nonlinear optics. In this paper, we theoretically analyze the accuracy and reliability of nonlinear methods and experimentally measure the refractive index of ordinary light at different wavelengths and temperatures in a non-critical phase matching LN crystal by the sum-frequency generation and spontaneous parametric down-conversion processes, with the help of the existing accurate Sellmeier equation for the refractive index of extraordinary light.
View Article and Find Full Text PDFJ Phys Chem Lett
January 2025
Molecular Spectroscopy Laboratory, RIKEN, 2-1 Hirosawa, Wako 351-0198, Japan.
Elucidation of the vibrational relaxation process of interfacial water is indispensable for understanding energy dissipation at the aqueous interface. In this study, the vibrational relaxation dynamics of the hydrogen-bonded OH (HB OH) stretch vibration was investigated at the air/isotopically diluted water (HOD-DO) interface by time-resolved heterodyne-detected vibrational sum frequency generation (TR-HD-VSFG) spectroscopy. We observed the temporal change of the excited-state band ( = 1 → 2 transition), which enables a reliable determination of the time of interfacial water.
View Article and Find Full Text PDFNanophotonics
January 2025
Institute of Physics, Swiss Federal Institute of Technology Lausanne (EPFL), CH-1015 Lausanne, Switzerland.
Sum-frequency generation (SFG) enables the coherent upconversion of electromagnetic signals and plays a significant role in mid-infrared vibrational spectroscopy for molecular analysis. Recent research indicates that plasmonic nanocavities, which confine light to extremely small volumes, can facilitate the detection of vibrational SFG signals from individual molecules by leveraging surface-enhanced Raman scattering combined with mid-infrared laser excitation. In this article, we compute the degree of second order coherence ( (0)) of the upconverted mid-infrared field under realistic parameters and accounting for the anharmonic potential that characterizes vibrational modes of individual molecules.
View Article and Find Full Text PDFACS Nano
January 2025
Department of Chemistry and Biochemistry, University of California San Diego, La Jolla, California 92093, United States.
The structure and dynamics of water at charged graphene interfaces fundamentally influence molecular responses to electric fields with implications for applications in energy storage, catalysis, and surface chemistry. Leveraging the realism of the MB-pol data-driven many-body potential and advanced path-integral quantum dynamics, we analyze the vibrational sum frequency generation (vSFG) spectrum of graphene/water interfaces under varying surface charges. Our quantum simulations reveal a distinctive dangling OH peak in the vSFG spectrum at neutral graphene, consistent with recent experimental findings yet markedly different from those of earlier studies.
View Article and Find Full Text PDFChembiochem
January 2025
School of Biological Science and Medical Engineering, State Key Laboratory of Digital Medical Engineering, Southeast University, Nanjing, 210096, P. R. China.
In recent years, antimicrobial peptides (AMPs) have emerged as a potent weapon against the growing threat of antibiotic resistance. Among AMPs, the ones containing tryptophan (W) and arginine (R) exhibit enhanced antimicrobial properties, benefiting from the unique physicochemical features of the two amino acids. Herein, we designed three hexapeptides, including WR, DWR (-isomer), and RF, derived from the original sequence, RWWRWW-NH (RW).
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