Streak camera detection system

In order to examine more closely the processes which determine , time-resolved fluorescence measurements on dyes adsorbed on semiconductor and glass surfaces were carried out in our laboratory. The first set of experiments used a low repetition rate, mode-locked Nd glass laser and streak camera detection (17). For rhodamine B adsorbed from 4 x 10 M aqueous solutions, we obtained Tj = 55 ps on Sn-doped In203 and = 46 ps on glass. Because these experiments were carried out at high, we concluded that the short on both surfaces was determined mostly by efficient energy transfer quenching. The low sensitivity of the experimental system did not permit experiments at low e. 

The commercially available laser source is a mode-locked argon-ion laser synchronously pumping a cavity-dumped dye laser. This laser system produces tunable light pulses, each pulse with a time duration of about 10 picoseconds, and with pulse repetition rates up to 80 million laser pulses/second. The laser pulses are used to excite the sample under study and the resulting sample fluorescence is spectrally dispersed through a monochromator and detected by a fast photomultiplier tube (or in some cases a streak camera (h.)) ... 

The time-resolved techniques that are usually used for FLIM are based on electronic-basis detection methods such as the time-correlated single photon counting or streak camera. Therefore, the time resolution of the FLIM system has been limited by several tens of picoseconds. However, fluorescence microscopy has the potential to provide much more information if we can observe the fluorescence dynamics in a microscopic region with higher time resolution. Given this background, we developed two types of ultrafast time-resolved fluorescence microscopes, i.e., the femtosecond fluorescence up-conversion microscope and the... 

Details of the picosecond pulse radiolysis system for emission (7) and absorption (8) spectroscopies with response time of 20 and 60 ps, respectively, including a specially designed linear accelerator (9) and very fast response optical detection system have been reported previously. The typical pulse radiolysis systems are shown in Figures 1 and 2. The detection system for emission spectroscopy is composed of a streak camera (C979, HTV), a SIT... 

Fig. 20. Schematic diagram of the Synchroscan streak camera system. A Spectra Physics model 164 acousto-optically mode-locked argon ion laser modulated at 69.44MHz pumps the Rhodamine 6G dye laser formed by mirrors Mi, M2, M3 and M4. This dye laser typically produces pulses of 2 ps duration with an energy content of 0.6 nJ. The second harmonic is generated intracavity in an ADP crystal. The UV radiation is then coupled out through mirror Ms and a filter F2 is used to eliminate any transmitted visible light before focusing into the sample cell with lens Lt. The fluorescence is detected at 90 to the incident beam. A lens L2 collects the fluorescence which passes through a polarizer and a bandpass filter and then onto the slit of the streak camera. (After ref. 69.)...

As described above, recent advances in accelerator technology have enabled the production of very short electron pulses for the study of radiation-induced reaction kinetics. Typically, digitizer-based optical absorbance or conductivity methods are used to follow reactions by pulse radiolysis (Chap. 4). However, the time resolution afforded by picosecond accelerators exceeds the capability of real-time detection systems based on photodetectors (photomultiplier tubes, photodiodes, biplanar phototubes, etc.) and high-bandwidth oscilloscopes (Fig. 8). Faster experiments use streak cameras or various methods that use optical delay to encode high temporal resolution, taking advantage of the picosecond-synchronized laser beams that are available in photocathode accelerator installations. 

The streak camera (1, 2) is a versatile method of fluorescence detection with picosecond resolution (3,4). The photocathode responds over a wide spectral range (190 nm to 850 nm for S-20), it responds equally to any polarization of light and is non-selective in terms of solid angle of incident light. These features combine to make the streak camera an attractive system for general use in picosecond photophysics. 

Transition radiation is considerably weaker than Cerenkov radiation, however since it is a surface phenomenon it avoids problems with radiator thickness and reflections inherent to Cerenkov-generating silica plates. Optical TR can be measured using a streak camera. An optical TR system has been used to time-resolve the energy spread of an electron macropulse in a free-electron laser facility [10]. Interferometry of coherent, far-infrared TR has been used to measure picosecond electron pulse widths and detect satellite pulses at the UCLA Satumus photoinjector, using charges on the order of 100 pC [11],... 

To study the carrier and vibrational relaxation dynamics, mode-locked laser systems, which provide femtosecond pulses and fast and sensitive detection systems are necessary. For detection, streak cameras are used for measurements with time resolution in the subpicosecond range or CCD cameras for time-integrated measurements. For the latter, time resolution can be achieved by using optical Kerr gates or upconversion [266,268]. In general, the two mainly used optical detection mechanisms for coherent phonons (optical, acoustical, or LO-plasmon coupled modes) are the pump/probe [280-285] and the four-... 

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