Ultrafast time-resolved images

Ultrafast Time-Resolved Near-Field Imaging of Gold Nanorods 45... 

We wish to show that ultrafast time-resolved photoelectron imaging (TR-PEI) together with nonadiabatic ab initio dynamics on the fly accounting for all degrees of freedom allows to elucidate precisely the photophysics and photochemistry of furan. Our theoretical simulation of photoionization is based on the methods described in Sects. 17.2 and 17.3. The theoretical analysis is focused on the time-dependent photoelectron signal intensity and PKE distribution. The complementary... 

L. Sandrin, S. Catheline, M. Tanter, X. Hennequin and M. Fink, Time-resolved pulsed elastography with ultrafast ultrasonic imaging, Ultrason. Imaging, 1999, 21, 259-272. 

As described in the previous section, the femtosecond fluorescence up-conversion microscope enabled us to visualize microscopic samples based on position-depen-dent ultrafast fluorescence dynamics. However, in the imaging measurements using the fluorescence up-conversion microscope, XY scanning was necessary as when using FLIM systems. To achieve non-scanning measurements of time-resolved fluorescence images, we developed another time-resolved fluorescence microscope. 

Beyond imaging, CARS microscopy offers the possibility for spatially resolved vibrational spectroscopy [16], providing a wealth of chemical and physical structure information of molecular specimens inside a sub-femtoliter probe volume. As such, multiplex CARS microspectroscopy allows the chemical identification of molecules on the basis of their characteristic Raman spectra and the extraction of their physical properties, e.g., their thermodynamic state. In the time domain, time-resolved CARS microscopy allows recording of ultrafast Raman free induction decays (RFIDs). CARS correlation spectroscopy can probe three-dimensional diffusion dynamics with chemical selectivity. We next discuss the basic principles and exemplifying applications of the different CARS microspectroscopies. 

The rate of polymerization and the cure penetration can be further increased by employing powerful lasers as radiation source, the exposure time dropping then into the millisecond range. Polymer relief images were thus obtained at micronic resolution by simply scanning the photosensitive plate with a highly focused laser beam. The kinetic profiles of such ultrafast reactions were directly record by using time-resolved infrared spectroscopy which allows instantaneous evaluation at any moment of the actual rate of polymerization and the precise amount of residual unsaturation in the cured polymCT. 

In summary, time-resolved photoelectron imaging spectroscopy with the very high time-resolution of 22 fs using two-colour deep UV pulses and ab initio nonadiabatic dynamics simulations have for the first time revealed the ultrafast deactivation processes from S2 to So state in furan. Joint theoretical and experimental results represent a general approach for investigation of ultrafast photochemical reactions, allowing to identify the fingerprints of the character of electronic states with an unprecedented precision. 

Figure 7.5 Ultrafast spectrally resolved dynamics of two CdS tSei x nanobelts. The fluorescence image is shown in the upper left corner. Note that the broad, time-integrated photoluminescence spectrum shown on the left consists of two distinct features centered at 628 and 636 nm with vastly different dynamics that is clearly discernible in the 2D map.

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