Ekspla PL2230型高能量皮秒激光器

采用立陶宛Ekspla公司PL2230型脉冲皮秒激光器和PG501-DFG1P型皮秒光学参量发生器构成的和频光谱测量系统（SFG）对运行中的OFET器件半导体/绝缘体界面处电荷活动状态进行了可视化测量。

采用立陶宛Ekspla公司的由PL2231-50型脉冲皮秒激光器，PG501-DFG1P高能光学参量发生器构成的和频光谱测量系统，对有机场效应晶体管半导体/绝缘体界面处累积电荷分布进行了实验测量研究。

采用Ekspla PL2230型锁模脉冲皮秒高能量激光器，搭建了一套皮秒振动和频光谱测量系统SFG，并利用该测量系统研究了固定化酶制备非均相酶杂化催化剂的课题

采用由立陶宛Ekspla公司的PL2231型高功率皮秒激光器和光学参量发生器等设备构成的振动和频光谱测量系统，对重负离子复合物在软电荷界面形成独特的水结构的现象进行了实验研究。

In numerous applications in microfluidics, cell growth, soft lithography, and molecular imprinting, the surface of poly(dimethylsiloxane) (PDMS) is modified from a hydrophobic methyl-terminated surface to a hydrophilic hydroxylterminated surface. In this study, we investigated molecular structural and orientational changes at the PDMS-air interface in response to three commonly used surface modification processes: exposure to long-wavelength ultraviolet light (UV), exposure to short-wavelength UV that generates ozone (UVO), and exposure to oxygen plasma (OP). The surfaces of two PDMS compositions (10:1 and 4:1 of base polymer/curing agent) were probed during modification, using monolayer-sensitive IR + visible sum frequency generation (SFG) vibrational spectroscopy, with two different polarization combinations. During PDMS surface modification, the peak intensities of CH3 side groups and CH2 cross-link groups decreased, while peak intensities of Si-OH groups increased. There was no significant change in the average orientation of the CH3 groups on the PDMS surface during modification. The concentration of CH3 groups on the surface decreased exponentially with time, for all three UV, UVO, and OP modification processes, with first order kinetics and time constants of approximately 160, 66, and 0.3 min, respectively. At steady state, residual CH3 groups were detected at the PDMS surface for UV and UVO treatments; however, there were negligible CH3 groups detected after OP modification.

We present a direct comparison of phase sensitive sum-frequency generation experiments with phase reconstruction obtained by the maximum entropy method. We show that both methods lead to the same complex spectrum. Furthermore, we discuss the strengths and weaknesses of each of these methods, analyzing possible sources of experimental and analytical errors. A simulation program for maximum entropy phase reconstruction is available at: http://lbp.epfl.ch/.

he nature of water's hydrogen-bonding network is a vital in fluence on the chemistry that occurs at interfaces, but a complete understanding of interfacial water has proven elusive. Even-order nonlinear optical spectroscopies, such as vibrational sum frequency generation (VSFG) spectroscopy and heterodyne detected phase-sensitive sum frequency generation (PS-SFG) spectroscopy, are inherently surface specific. With the advent of advances in these spectroscopic techniques, researchers can now explore many longstanding questions about the dynamics and structures present at the vapor
water and water
solid interfaces. Of special interest to the atmospheric chemistry community is the accommodation of ions and solutes by water's hydrogen-bonding network. A better understanding of how ions and solutes behave in hydrogen-bonded water has afforded a fresh perspective of aqueous aerosols, because the interactions involved therein drive phenomena such as the hydrolysis of atmospheric chemical species. In this Account, we present work from our laboratory focusing on applying VSFG and the recently developed PSSFG techniques to probe the perturbation ofwater's hydrogen-bonding network at the vapor
water interface by a variety of ions and solutes. We also present very recent results from our laboratory on the direct observation of the adsorption of ions at the water
CaF2 interface.

Recent advances in the performance of organic semiconductors such as organic light emitting diodes (OLEDs), organic field-effect transistors (OFETs), and organic solar cells have been dramatic. In particular for OLEDs, stability and durability have improved to levels that warrant their application in everyday life. In organic devices, the charge carriers, both electrons and holes, often have to be injected through organic/electrode interfaces. Therefore, an understanding of the interaction between metal electrode and organic molecules is quite important, because the electronic properties of metal/organic interface directly affect the performance of the OLEDs.

采用立陶宛Ekspla公司的PL2231C-20, 20 Hz, 80 ps,532 nm, >15 mJ/pulse 激光器做光源，采用LaVision公司的sCMOS (2560 x 2160 pixels, 6.5 gm pixel pitch,16-bit depth) 相机。采用四波混频，相位共轭镜补偿等技术实现消除激波密度不均匀性干扰的相干成像。

In this work multimodal operation of commercially available CARS microspectrometer (EKSPLA CARSCOPE) equipped with a picosecond dual wavelength laser source (EKSPLA PT259) was demonstrated for the imaging of various biological objects using coherent anti‑Stokes Raman scattering (CARS), two photon excited fluorescence (TPEF) and second harmonic generation (SHG) contrast mechanisms. Obtained CARS‑images of yeast cell and flower pollen clearly demonstrate label‑free and 3D imaging capabilities of CARS technique. Multi‑contrast images of green algae and plants containing starch demonstrate a variety of research facilities, where the method can be applied.

Electric field reversals in single and dual-frequency capacitively coupled radio frequency discharges are investigated in the collisionless (
1 Pa) and the collisonal (65 Pa) regimes. Phase resolved optical emission spectroscopy is used to measure the excitation of the neutral background gas caused by the field reversal during sheath collapse. The collisionless regime is investigated experimentally in asymmetric neon and hydrogen single frequency discharges operated at 13.56MHz in a GEC reference cell. The collisional regime is investigated experimentally in a symmetric industrial dual-frequency discharge operated at 1.937 and 27.118 MHz. The resulting spatio-temporal excitation profiles are compared with the results of a fluid sheath model in the single frequency case and a particle-in-cell/Monte Carlo simulation in the dual-frequency case. The results show that field reversals occur in both regimes. An analytical model gives an insight into the mechanisms causing the reversal of the electric field. In the dual-frequency case a qualitative comparison between the electric fields resulting from the PIC simulation and from the analytical model is performed. The field reversal seems to be caused by different mechanisms in the respective regimes. In the collisionless case it is caused by electron inertia, whereas in the collisional regime it is caused by a combination of the low mobility of electrons due to collisions and electron inertia. Finally, the field reversal during the sheath collapse seems to be a general source for energy gain of electrons in both single and dual-frequency discharges.

Stability of the Si-H bonds on the hydrogen-terminated Si(111) surface has been investigated by sum frequency generation (SFG) spectroscopy in air at room temperature. The SFG observation showed that the Si(111) surface is terminated by a monolayer of monohydride (Si-H) after etching in a concertrated ammonium fluoride (NH4F) solution. The number of Si-H bonds decreased with laser irradiation time and the abstraction rate of hydrogen atoms on Si increased with the increase of input energy of "visible" light. The Si-H bond under irradiation at 1064nm light was more stable than that at 532nm light with a given intensity. A small amount of water in air severely lowered the stability of Si-H bond because of a photoelectrochemical recation under laser irradiation.

The orientation, structure, and energetics of the vapor/acetone-water interface are studied with sum frequency generation vibrational spectroscopy (SFG-VS). We used the polarization null angle (PNA) method in SFGVS to accurately determine the interfacial acetone molecule orientation, and we found that the acetone molecule has its CdO group pointing into bulk phase, one CH3 group pointing up from the bulk, and the other CH3 group pointing into the bulk phase. This well-ordered interface layer induces an antiparallel structure in the second layer through dimer formation from either dipolar or hydrogen bond interactions. With a double-layer adsorption model (DAM) and Langmuir isotherm, the adsorption free energies for the first and second layer are determined as ¢G°ads,1 ) - 1.9 ( 0.2 kcal /mol and ¢G°ads,2 ) - 0.9 ( 0.2 kcal /mol, respectively. Since ¢G°ads,1 is much larger than the thermal energy kT ) 0.59 kcal /mol, and ¢G°ads,2 is close to kT, the second layer has to be less ordered. Without either strong dipolar or hydrogen bonding interactions between the second and the third layer, the third layer should be randomly thermalized as in the bulk liquid. Therefore, the thickness of the interface is not more than two layers thick. These results are consistent with previous MD simulations for the vapor/pure acetone interface, and undoubtedly provide direct microscopic structural evidences and new insight for the understanding of liquid and liquid mixture interfaces. The experimental techniques and quantitative analysis methodology used for detailed measurement of the liquid mixture interfaces in this report can also be applied to liquid interfaces, as well as other molecular interfaces in general.

Polarization null angle (PNA) method is an accurate alternative to the commonly used polarization intensity ratio method in determination of molecular orientation at interfaces with sum frequency generation vibrational spectroscopy (SFG-VS). Here, the accuracy and sensitivity of PNA method is tested on different experimental configurations. It is found that its accuracy and sensitivity are more sensitive to the incident angle of the visible beam than the IR beam, and the range of the optimal experimental configurations is identified. This development makes better understanding of the polarization measurement in SFG-VS, and should find more applications for interface studies.