Michael Schmitt

Frames, decisions, and cardiac-autonomic control

The “framing effect” (FE) describes the phenomenon whereby human choices are susceptible to the way they are presented rather than objective information. The present study extends common decision-making paradigms with frame variation by including inhibitory control, operationalized as vagally mediated heart rate variability (HRV) at rest and motor response inhibition during a stop-signal task (SST). We hypothesized that inhibitory control is inversely associated with susceptibility to framing effects. Forty adult volunteers performed a risky-choice framing task in which identical information about wins and losses was presented using loss or gain frames. As predicted, there was an inverse association between HRV and framing effects, accounting for 23% of the variance in framing effects. Inhibitory control as indexed by performance in the SST was not associated with framing effects. These results are discussed in terms of the role of inhibitory processes (as indicated by vagal activity) for decision-making processes.

Continuous-Wave Crystalline Raman Lasers

Continuous- wave generation of Ba(NO3)2 Raman laser pumped by multimode argon laser and diode pumped Nd:KGW and Nd:YVO4 lasers with Raman conversion is investigated. Output Stokes power and generation efficiency reached 160 mW and 5%.

Femtosecond spectroscopy on simple molecular systems: pump-probe and four-wave mixing techniques

Different techniques are applied in order to obtain information about ultrafast molecular and reaction dynamics. Femtosecond time-resolved pump-probe spectroscopy is used to investigate the dissociation reaction of NAI molecules. Starting from free NaI molecules, the environment is changed to solution-like conditions adding rare gas with different pressures. Femtosecond time-resolved degenerate four-wave mixing (DFWM) spectroscopy is performed in order to investigate molecular dynamics in iodine molecules in the gas phase. Depending on the timing of the laser pulses different dynamics are reflected in the DFWM transient signal. By the use of time evolution diagrams, the varying contribution of ground and excited-state dynamics can be explained conclusively. Supersonic jet-cooled potassium dimers are investigated in their electronic ground state by a femtosecond pump-probe experiment. The ground state vibrational wave packets are created by a stimulated Raman pumping process and selectively interrogated by resonance enhanced three photon ionization.

Raman meets medicine: Raman spectroscopy: a powerful tool in biophotonics

Biophotonics is a new and highly interdisciplinary scientific discipline comprising the application of light (i.e. innovative photonic tools) in life sciences. It is non exaggerated to say Biophotonics is on the way to solve the most important problems in biomedicine. In particular Raman microspectroscopy allows one to derive detailed and specific information on a molecular level which other photonic methods methods can only provide by a limited extent. Here we will present latest results of our own research dealing with the application and development of innovative Raman spectroscopic techniques for biomedical applications.

Au Ion Induced Modification of C60 Thin Film Samples

The present work reports phase transformations of thin films of C 60 irradiated with 100 MeV 197 Au 8+ ions. This work is in continuation with our earlier work using 58 Ni 10+ and 16 O 6+ ions, to study the modification in C 60 thin films. The study of C 60 thin films using 197 Au 8+ ions, provides us enough additional data to investigate thoroughly the role of S e in causing phase transformations under different ion fluences. The Raman spectra indicate that swift heavy ion (SHI) irradiation results in several transformations of crystalline C 60 . At low fluences along with the fragmentation of C 60 there is dimer/polymer formation. As fluence increases the dimer/polymer content first rises, optimizes, decreases and finally vanishes at very high fluences. At high fluences, all the C 60 molecules as well as the polymer C 60 break up, possibly resulting in nano-crystalline graphite embedded in amorphous carbon (a-C).