Dr. Csaba Janáky (group leader, senior research fellow)
Dr. Viktor Chikán (senior research fellow)
Dr. Károly Mogyorósi (research fellow)
Dr. Gergely Samu (research fellow)
Krisztina Sárosi (early-stage researcher)
Ultrafast Dynamics Group probes ultrafast charge carrier dynamics at semiconductor interfaces and in nanoparticles and aims at controlling chemical and physical processes with light.
To probe ultrafast charge carrier dynamics at semiconductor interfaces we are developing novel tools which allow to carry out laser-driven spectroscopic experiments under electrochemical control. We are combining electrochemistry with different pump-probe techniques (e.g., time-resolved fluorescence, THz absorption, mid-IR). These methods will allow us to better understand the charge transfer processes at solid/solid and solid/liquid interfaces, thus accelerating solar energy research. Furthermore, the perturbation from the strong terahertz electric field will allow studying the dynamical properties of electrons in polarizable systems, like doped semiconductor quantum dots and metallic nanoparticles exhibiting electrons delocalized on several thousand atoms. Besides studying relaxation dynamics of charge carriers in the presence of strong optical bias, we aim at exploring fundamental steps needed to generate higher harmonic radiation from nanoparticles.
Another aim of the group is the control of chemical reactions and charge transfer utilizing terahertz light pulses in the condensed and the gas phase. Our group is interested in how the terahertz electric field can be efficiently used during the simplest chemical reactions so called photodissociation reactions initiated by intense XUV pulses: the high intensity, quasi static terahertz pulse will enable us to influence conical intersections based on the polarizability of the various excited states accessed during XUV photodissociation. We will investigate how tunneling reactions involving light fragments such as proton or electron can be significantly manipulated with the help of intense static electric fields.
Transient Absorption/Reflection Spectrometer (TAS) is an instrument for femtosecond pump-probe spectroscopy. TAS incorporates highest quality optics, opto-mechanics, Fourier Transform spectrograph, optical chopper, vibration control, delay-line stage, and easy-to-use LabVIEW™ based software to deliver results. TAS can be upgraded and reconfigured to support many other ultrafast spectroscopy techniques as your research needs evolve.
Sample types and conditions for TAS measurements
Available Light Sources:
Reaction Chamber for gas phase pump (XUV/DUV/UV/IR/Terahertz) and Chemiluminescence (UV/VIS/NIR/IR) probe experimental setup is capable of studying photodissociation processes and chemical reaction between radicals in the gas phase. The chemiluminescence spectrum is detected by a Fourier Transform Spectrometer capable of operating in step scan mode to obtain time-resolved spectra.
R. Flender, A. Börzsönyi, V. Chikán
Phase-controlled, second harmonic optimized THz pulse generation in nitrogen by infrared two-color laser pulses
J. Opt. Soc. Am. B
K. Mogyorósi, K. Sárosi, I. Seres, P. Jójárt, M. Füle, and V. Chikán
Formation of CN Radical from Nitrogen and Carbon Condensation and from Photodissociation in Femtosecond Laser-Induced Plasmas: Time-Resolved FT-UV−Vis Spectroscopic Study of the Violet Emission of CN Radical
J. Phys. Chem. A, 124, 2755−2767, 2020
R. Flender, K. Sárosi, E. Petrács, A. Börzsönyi, V. Chikán
Controlling terahertz spectrum in asymmetric air plasmas: the role of GDD and phase
Proc. SPIE 10684, Nonlinear Optics and its Applications 2018, 1068428
R. A. Scheidt, G. F. Samu, Cs. Janáky and P. V. Kamat
Modulation of Charge Recombination in CsPbBr3 Perovskite Films with Electrochemical Bias
J. Am. Chem. Soc., 140, 86--89, 2018
Gergely F. Samu, Rebecca A. Scheidt, Prashant V. Kamat , Csaba Janáky
Electrochemistry and Spectroelectrochemistry of Lead Halide Perovskite Films: Materials Science Aspects and Boundary Conditions
Chemistry of Materials
R. Flender; K. Sárosi; A. Börzsönyi; V. Chikán
The impact of dispersion of the ultrashort light pulses on the THz radiation formation from asymmetric air plasmas
Proc. SPIE 10228, Nonlinear Optics and Applications 2017, 102281B