Ultrafast gating

Trebino R and Kane D J 1993 Using phase retrieval to measure the intensity and phase of ultrafast pulses frequency-resolved optical gating J. Opt. Soc. Am. A 10 1101-11... 

Kahlow MA, Jarzeba W, DuBruil TP, Barbara PF. Ultrafast emission spectroscopy in the ultraviolet by time-gated upconversion. Rev. Sci. Instrum. 1988 59 1098-1109. 

The apparatus can be divided into three main sections, laser-pulse production, amplification, and fluorescence upconversion. The ultrafast lasers employed for upconversion are those that have been described above. The experiment is a crosscorrelation between the fluorescence pulse and the laser pulse. At time t = 0, the sample is excited by the ultrafast laser pulse. The resulting incoherent fluorescence (frequency = coa) is collected and mixed in a nonlinear crystal (such as KDP) with the gating pulse (frequency = cui) derived from the excitation source and arriving at time t = z. This frequency mixing of the fluorescence and probe beams generates light at the sum frequency, cosum... 

The spectra were recorded both through the overlying skin and directly on bare bone using the ultrafast Raman Kerr-gated method, (a) Raman spectra of wild-type mice (b) Raman spectra of oimfoim mice (c) Difference... 

Ultrashort fluorescence lifetimes are best determined by photon upconversion. An excellent description of the technique for non-specialists wishing to set up an experiment is in preparation as part of a current IUPAC project on ultrafast intense laser chemistry .181 The time resolution is basically limited by the temporal width of the laser pulses that are being used. An intense gate pulse at frequency vq is mixed with the fluorescence at a frequency vp in a nonlinear optical crystal (Special Topic 3.1), to create a short pulse at the sum frequency i j. The gate pulse thus represents a time window for the fluorescence... 

Zaidat O et al (2002) The utility of ultrafast cardiac cycle gated and contrasted spiral computerized axial chest tomography in evaluation of patients with acute stroke and comparison with transesophageal echocardiography. Proceedings of the 27th International Stroke Conference. American Stroke Association, San Antonio, TX. 

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