Molecular rotation in 3 dimensions at an air/water interface using femtosecond time resolved sum frequency generation

Abstract

Development of ultrafast broadband electronic sum frequency generation for charge dynamics at surfaces and interfaces

Polarization-Dependent Heterodyne-Detected Sum-Frequency Generation Spectroscopy as a Tool to Explore Surface Molecular Orientation and Ångström-Scale Depth Profiling

“…Furthermore, such a PD-SFG technique has not been combined with the time-resolved SFG technique, 34 , 97 − 99 except for some studies. 59 , 100 − 102 Founding a theoretical basis for time-resolved PD-HD-SFG and its demonstration will be an interesting next challenge for the SFG community.…”

“…The HD-SFG measurement on the sps , pss , and ppp polarization combination and chiral polarization , is on the horizon. Furthermore, such a PD-SFG technique has not been combined with the time-resolved SFG technique, ,− except for some studies. ,− Founding a theoretical basis for time-resolved PD-HD-SFG and its demonstration will be an interesting next challenge for the SFG community.…”

Photo-Voltage Transients for Real-Time Analysis of the Interactions between Molecules and Membranes

“…In the past few decades, nonlinear optical techniques such as the second harmonic generation (SHG) and sum-frequency generation (SFG) methods have been extensively developed for characterizing interfacial structures and interactions. − These methods originate from induced polarization rather than real absorption, employ nonresonant optical interactions, and therefore promise a noninvasive, low-phototoxic, and ideal candidate for in situ imaging of biological interfaces. Specifically, recent developments of these methods have further improved their spatial (e.g., at the molecular level) and temporal resolutions to higher levels (e.g., less than one second for each spectrum by femtosecond SFG spectroscopy). , In brief, all of these experimental techniques have their own advantages and limitations, and an in situ, noninvasive, sensitive, and easy-to-handle technique is still needed for real-time monitoring of the dynamic processes at the biological interfaces, which is challenging for most present techniques.…”

“…Specifically, recent developments of these methods have further improved their spatial (e.g., at the molecular level) and temporal resolutions to higher levels (e.g., less than one second for each spectrum by femtosecond SFG spectroscopy). 37,38 In brief, all of these experimental techniques have their own advantages and limitations, and an in situ, noninvasive, sensitive, and easy-tohandle technique is still needed for real-time monitoring of the dynamic processes at the biological interfaces, which is challenging for most present techniques.…”

Interface-Specific Two-Dimensional Electronic Sum Frequency Generation Spectroscopy

“…Even-order nonlinear optical spectroscopies exhibit intrinsic surface/interface selectivity. Some of these techniques have been utilized for investigating molecular ordering, orientations, and dynamics of chemical, materials, environmental, and biological systems at surfaces and interfaces. − For instance, second-order sum frequency generation (SFG) and second harmonic generation (SHG) spectroscopy has been used to study the structure, configurations, and chemical reactions of interfacial molecules for more than 30 years. − ,,− Recently, structural dynamics at surfaces and interfaces have been explored using time-resolved SFG and SHG thanks to the development of ultrafast lasers. ,− A higher fourth-order surface/interface specific spectroscopy has the potential to provide more structural and dynamical information about surfaces and interfaces. A fourth-order spectroscopy, two-dimensional vibrational SFG (2D-VSFG) spectroscopy, has been demonstrated a few years ago. − Furthermore, heterodyne 2D-VSFG spectroscopy using mid-IR pulse shaping and noncollinear geometry 2D-VSFG experiments have been also developed to study vibrational structures and dynamics at the interface. − However, fourth-order spectroscopy techniques of electronic nature, two-dimensional electronic sum frequency generation spectroscopy (2D-ESFG), have not been demonstrated yet.…”