Photonics probes

Vo-Dinh T., Surface-Enhanced Raman Spectroscopy, in Photonic Probes of Surfaces, Halevi P. ed., Elsevier, New York, 1995. 

Abe, S. 2001. Two-photon probe of forbidden exciton states in symmetric aggregates of asymmetric molecules. Chem. Phys. 264 355-63. 

Figure 4. Schematic of the potential energy curves of the relevant electronic states The pump pulse prepares a coherent superposition of vibrational states in the electronic A 1 EJ state at the inner turning point. Around v = 13 this state is spin-orbit coupled with the dark b 3n state, causing perturbations. A two-photon probe process transfers the wavepacket motion into the ionization continuum via the (2) llg state [7].

Figure 5. Wavepacket motion of the 39,39 K2 A state interrogated by (a) a two-photon probe pulse via the (2) 1 IIg state and (i>) a one-photon probe process into the ionization continuum (c, d) corresponding Fourier transforms, indicating a stronger second harmonic for the one-photon probe process [7].

Figure 8. Time-resolved photoelectron spectra revealing vibrational and electronic dynamics during internal conversion in DT. (a) Level scheme in DT for one-photon probe ionization. The pump laser prepares the optically bright state S2. Due to ultrafast internal conversion, this state converts to the lower lying state Si with 0.7 eV of vibrational energy. The expected ionization propensity rules are shown S2 —> Do + e (ei) and Si —> D + (b) Femtosecond time-...

Positronium can pick-off an electron during a collision with a pore wall and annihilate into two photons. Between collisions, only three photon annihilations occur, just as in vacuum. Quantum mechanically, the overlap with the wall-electron wave functions decreases with the distance from the wall and pick-off (two photons) becomes less likely. With increasing pore size collisions become less frequent. The ratio of 3 photon annihilations to 2 photons probes the combination of pore size and total pore volume as well as their link to the sample surface, and can be measured by examining the energy distribution of annihilation photons. This 3-to-2 photon ratio can be calibrated to absolute fractions of positronium in the annihilation spectrum [16, 17]. 

The lower trace of Fig. 3a displays the NeNePo signal for 6.1-eV two-photon probe energy (Epr2ph) measured at 20 K. The measured Ag2Au+ ion intensity is lowest around zero time, when pump and probe pulse overlap temporally. The... 

P. Halevi (Ed.), Photonic Probes of Surfaces, Chap. 2, Elsevier Science, Amsterdam, 1995,... 

Reider G A and Heinz T F 1995 Second-order nonlinear optical effects at surfaces and interfaces recent advances Photonic Probes of Surfaces ed P Halevi (Amsterdam Elsevier) pp 413-78... 

Photon Probe Techniques, divided further according to the fundamental process used ... 

From one-photon to two-photon probes Caged compounds, actuators, and photoswitches (among the probes are N- and O-heterocycles) 13AG(E)4526. 

Noy A, HuserTR. (2003) Combined force and photonic probe microscope with single molecule sensitivity. Rev Sci Instrum 7A-. 1217—1221. 

Fauster, T. and Steinmann, W. (1995) Two-photon photoemission spectroscopy of image states, in Electromagnetic Waves Photonic Probes of Surfaces vol. 2, (ed. P. Halevi), North-Holland, Amsterdam, p. 347-411. 

Fauster, Th. and Steinmann, W. (1995) Photonic Probes of Suijaces, Electromagnetic Waves Recent Developments... 

In addition to photonic switches, photonic proteins were engineered to contain fluorescent moieties that react to changes in a protein s local environment and to conformational changes. In this section, we review several examples of designing photonic probes that goes beyond simple chemical labeling and cysteine mutagenesis. 

FIGURE 133.4 Incorporation of photonic probes into proteins via expressed protein ligation (F = fluorescent probe). This approach involves a very specific chemical reaction between thioester on one polypeptide fragment and the N-terminal cysteine moiety on the other. Initial intermediate cysteine thioester is converted into native peptide bond by intramolecular reaction. The original free SH group of the cysteine is also regenerated. 

An alternative approach to site-specific introduction of photonic probes relies on the selective oxidation of iV-terminal serine or threonine to an aldehyde followed by specific reaction with aromatic amines or hydrazine derivatives (hydrazides, thiosemicarbazide). Ketone moieties can also be generated by metal-catalyzed transamination reaction. ... 

As discussed previously, chemical synthesis allows a more general method of introducing site-specific photonic probes into polypeptides that is normally not possible using recombinant-DNA-based methods. However, chemical peptide synthesis is limited to peptides of 50 to 100 amino acid residues. In order to circumvent this limitation, an approach termed native chemical Kgation was developed, which is based on the chemoselective reaction of unprotected peptide segments in water at pH 7 to form amide-linked polypeptide products. 

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