Laser spectroscopy schematic

Recently, the electron-transfer kinetics in the DSSC, shown as a schematic diagram in Fig. 10, have been under intensive investigation. Time-resolved laser spectroscopy measurements are used to study one of the most important primary processes—electron injection from dye photosensitizers into the conduction band of semiconductors [30-47]. The electron-transfer rate from the dye photosensitizer into the semiconductor depends on the configuration of the adsorbed dye photosensitizers on the semiconductor surface and the energy gap between the LUMO level of the dye photosensitizers and the conduction-band level of the semiconductor. For example, the rate constant for electron injection, kini, is given by Fermi s golden rule expression ... 

The schematic view of the Mainz apparatus for collinear laser spectroscopy, installed at Isolde is given in fig 4. The 60 keV ion beam is set collinear with the laser beam, then accelerated (or decelerated) and finally neutralized in charge exchange cell. By Doppler tuning the atomic absorption is set resonnant with the stabilized laser frequency, and the fluorescence emitted is detected. 

Fig. 8. Schematic of setup used for co-linear laser spectroscopy on N5+...

Figure 1. Schematic experimental set-up for coincidence collinear laser spectroscopy.

Fig. 4. Ion dip spectroscopy schematic. R2PI is used to ionize and mass-select the cluster, Mx of interest. A second laser pulse, prior or coincident to ionization, excites an intermediate level (Sm), which depletes the ground state and reduces the ion signal of...

In Raman spectroscopy (cf., e.g., [183-187]), the strayUght spectrum is recorded of a sample which is irradiated with monochromatic light (produced, e.g.,by a laser). A schematic representation of the Raman scattering experiment is shown in Fig. 10. 

Figure 10.2 Time-resolved spectroscopy involving pump probe lasers, (a) Schematic of the experimental setup. The pump laser irradiates the sample with a fixed beam path. The timing of the probe laser is controlled by using a moveable mirror (mirrors I and II) system, (b) The pump laser excites molecules from the 5 state to the 5, state, and the probe laser excites the molecule from the 5 state to the ionization continuum. Molecules in the 5, state can undergo relaxation back to the 5n state...

Figure 27.11 Schematics ULustrating the relationship between the distribution of nascent photo-excited electrons and the state density in a metal (see also Figure 27.3). The excited electrons are classified as sub-vacuum electrons (fj <0eV) and photoelectrons (f(->0eV). Adapted from Zhou et at, in Laser Spectroscopy and Photo-Chemistry on Metal Surfaces, II, 1995, with permission of World Scientific Publishing Co...

Ffsurel. Schematic setup for col-linear laser spectroscopy (a) The superimposed laser and ion beams pass through the interaction and fluorescence detection region at a variable potential, (b) Neutralized beams are post-accelerated or decelerated by a potential at the charge-exchange cell. The beams may travel either in the same or in opposite directions. 

It is noticeable that the shortenings of the Pt-Pt and Pt-P distances, A(Pt-Pt) and A(Pt-P), of the Pn and Bzte crystals are 0.0081(3) and 0.005(1)A, and 0.0127(5) and 0.008(1) A, respectively, which are the largest two among the five crystals. The ratios of A(Pt-Pt) / A(Pt-P) are 1.62 and 1.59 for the Pn and Bzte crystals, respectively, which are very close to each other. This suggests that the excited diplatinum complex anion may have the same structure in the two crystals, and the concentrations of the excited molecules may be different between the two crystals. On the other hand, the excited structures in the Bu, Bztbu and Bzdmp crystals may be different due to the different crystal environment. The change at the excited state is schematically drawn in Fig. 7.26. Not only the Pt-Pt distance but also Pt-P distance is shortened at the excited state of the diplatinum complex anion, which is in good agreement with the experimental results observed from the combination of the EXAFS method with rapid-flow laser spectroscopy [54]. 

Presently, studies of elonentary processes in a static reactor gained a wide use because of the development of the pulse technique of the creation and detection of active species. With the development of the sensitivity and time resolution of laser spectroscopy methods, possibilities of studies in a static reactor were extended. These possibilities are described schematically in Table 3.1. 

Schematic diagram o apparatus for laser spectroscopy using optical heterodyne techniques.

Figure Bl.2.9. Schematic representation of the metliod used in cavity ringdown laser absorption spectroscopy. From [33], used with pemhssion.

Figure C3.5.3. Schematic diagram of apparatus used for (a) IR pump-probe or vibrational echo spectroscopy by Payer and co-workers [50] and (b) IR-Raman spectroscopy by Dlott and co-workers [39]. Key OPA = optical parametric amplifier PEL = free-electron laser MOD = high speed optical modulator PMT = photomultiplier OMA = optical multichannel analyser.

We use laser photofragment spectroscopy to study the vibrational and electronic spectroscopy of ions. Our photofragment spectrometer is shown schematically in Eig. 2. Ions are formed by laser ablation of a metal rod, followed by ion molecule reactions, cool in a supersonic expansion and are accelerated into a dual TOE mass spectrometer. When they reach the reflectron, the mass-selected ions of interest are irradiated using one or more lasers operating in the infrared (IR), visible, or UV. Ions that absorb light can photodissociate, producing fragment ions that are mass analyzed and detected. Each of these steps will be discussed in more detail below, with particular emphasis on the ions of interest. 

Figure 1. Schematic illustration of the laser-vaporization supersonic cluster source. Just before the peak of an intense He pulse from the nozzle (at left), a weakly focused laser pulse strikes from the rotating metal rod. The hot metal vapor sputtered from the surface is swept down the condensation channel in dense He, where cluster formation occurs through nucleation. The gas pulse expands into vacuum, with a skinned portion to serve as a collimated cluster bean. The deflection magnet is used to measure magnetic properties, while the final chaiber at right is for measurement of the cluster distribution by laser photoionization time-of-flight mass spectroscopy.

Figure 12.1 Schematic of the spectroelectrochemistry apparatus at the University of Dlinois. The thin-layer spectroelectrochemical cell (TLE cell) has a 25 p.m thick spacer between the electrode and window to control the electrolyte layer thickness and allow for reproducible refilbng of the gap. The broadband infrared (BBIR) and narrowband visible (NBVIS) pulses used for BB-SFG spectroscopy are generated by a femtosecond laser (see Fig. 12.3). Voltammetric and spectrometric data are acquired simultaneously.

Laser radiation can be obtained nowadays over a wide spectral range from the ultraviolet to the far infrared region, covering the range of optical spectroscopy. Fignre 2.4 shows schematically the spectral zones covered by different types of lasers. Although there are some specific regions in which direct laser action is not available. 

Fig. 5. Schematic represntation of equipment for laser-polarized Xe in NMR spectroscopy. Reproduced with peimission from (J6). Copyright 1999 American Chemical Society.

Fig. 3.5. Schematic diagram of conventional SORS and inverse SORS concepts showing Raman collection and laser beam delivery geometries (reprinted with permission from [34], Copyright (2006) The Society for Applied Spectroscopy)...

Figure 15.5 Schematic of instrumental apparatus. The DT/MH-functionalized AgFON was surgically implanted into a rat with an optical window and integrated into a conventional laboratory Raman spectroscopy system. The Raman spectroscopy system consists of a Ti sapphire laser (Acx = 785 nm), band-pass filter, beam-steering optics, collection optics, and a long-pass filterto reject Raleigh scattered light. All of the optics fit on a 4 ft x 10 ft optical table.

Time-resolved spectroscopy is performed using a pump-probe method in which a short-pulsed laser is used to initiate a T-jump and a mid-IR probe laser is used to monitor the transient IR absorbance in the sample. A schematic of the entire instrument is shown in Fig. 17.4. For clarity, only key components are shown. In the description that follows, only those components will be described. A continuous-wave (CW) lead-salt (PbSe) diode laser (output power <1 mW) tuned to a specific vibrational mode of the RNA molecule probes the transient absorbance of the sample. The linewidth of the probe laser is quite narrow (<0.5 cm-1) and sets the spectral resolution of the time-resolved experiments. The divergent output of the diode laser is collected and collimated by a gold coated off-axis... 

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