Atomic, Molecular & Optical Physics (AMO) Projects
Imaging Infrared Laser Source Development (Laser Engineering, Experimental)
E-mail: blaga@phys.ksu.edu
Earlier this year, the Macdonald Laboratory received a state of the art laser system operating at 100 kHz repetition rate, generating 450 femtoseconds, 3 milijoule pulses at a wavelength of 1030 nm. During the Summer 2024, our group will use this laser as a front end for developing a tunable midinfrared laser that will operate at 1.4-4 µm. In essence, in this project we will split the 1030 nm photons into two smaller ones, generating laser light at longer wavelengths in the process. Our group plans to use the new wavelengths to study ultrafast molecular dynamics when the target is irradiated with vibrationally resonant radiation.
For this hands-on project, the REU student will work closely with our group members in the laboratory. The project is multidisciplinary, covering undergraduate-level optics (electromagnetic waves, lenses and mirrors, prisms, polarization, image formation, etc.), nonlinear optics (white light continuum generation, difference frequency mixing), laser physics (laser propagation, laser beam profile measurements, ultrafast laser pulse characterization), and some elements of mechanical engineering (optomechanics and motion control). By the end of the summer, we plan to have a fully operational infrared laser source that we will test in a real experiment, measuring photoelectron spectra of small molecules like methane at wavelengths around 3 µm.
Notes: This laser development project is too complex for an REU student to handle alone. Thus, the REU student must be able to work closely with members of our group, including myself. In addition, the lasers used in this project require full compliance with laser safety and the presence in the laboratory is only permitted after completion of laser safety training.References
Leshchenko et al., ”High-power few-cycle Cr:ZnSe mid-infrared source for attosecond soft x-ray physics”, Optica, Vol. 7, Issue 8, pp. 981-988 (2020). https://doi.org/10.1364/OPTICA.393377
Camper et al., “Tunable mid-infrared source of light carrying orbital angular momentum in the femtosecond regime”, Optics Express, Vol. 42, Issue 19, pp. 3769-3772 (2017). https://doi.org/10.1364/OL.42.003769
Computational Ultrafast Dynamics for Molecules (Theory)
E-mail: lgreenman@phys.ksu.edu
The dynamics of molecules interacting with intense, ultrafast, or high-photon-energy laser fields pushes the frontier of complexity that can be described by current theories and computational techniques. However, it is precisely these regimes where we can learn new phenomena for molecules relevant to chemical reactivity and energy conversion. In this project, a 2023 REU student will explore new techniques for understanding molecular interactions on ultrafast timescales and complex dynamical processes.
Together, we will work with experimentalists at the James R. Macdonald Laboratory to understand complex processes by characterizing the potential energy of molecules at distorted geometries and in highly excited states. The student will learn to use state-of-the-art methods from the community of quantum chemistry, where quantum mechanics and applied mathematics are combined and applied to molecules. In the course of this project, we will use some of the most powerful supercomputers in the world including those at the National Energy Research Supercomputing Center (NERSC). Benefits include exposure to computer scripting in languages like Python, basic computer programming in Fortran or C++, and high-performance computational techniques.
Listening to the Voice of Photons in Intense Ultrashort Laser Pulses (Experimental)
E-mail: mengh@phys.ksu.edu
Do you want to know how to characterize an ultrashort femtosecond laser pulse? Are you tired of FROG or SPIDER technique?
During the 2023 REU program, our research group will develop a disruptive technology to characterize the femtosecond laser pulses, which is based on the voice of laser-induced plasma in air. In this project, you will learn how to control a delay stage, microphone, spectrometer by Labview programming and make a device!
E-mail: mengh@phys.ksu.edu
Do you want to play with a Yb-based solid-state industrial-level laser? Do you want to know how to generate the shortest scientific-level laser pulse from the industrial-level laser?
During the 2023 REU program, our research group will construct a post compression setup to transform an industrial-level laser pulse to the state-of-the-art scientific-level single-cycle laser. In this project, you will learn how to design the optical beam path, numerically calculate and experimentally control the dispersion of pulses!
Notes: It is important to note that the specific involvement of the REU student in any of the projects will depend on the qualifications and interests of the student as well as our needs at the time.References
[1] Jintai Liang+, Meng Han*+, Yijie Liao+, Jia-Bao Ji, Leung Chung Sum, Wei-Chao Jiang, Kiyoshi Ueda, Yueming Zhou*, Peixiang Lu*, Hans Jakob Wörner, "Attosecond-resolved Non-dipole Photoionization Dynamics", Nature Photonics (2024) .
[2] Meng Han*, Jia-Bao Ji, Chung Sum Leung, Kiyoshi Ueda, Hans Jakob Wörner*, "Separation of Photoionization and Measurement-induced Delays" Science Advances 10, eadj2629 (2024)
[3] Meng Han*, Jia-Bao Ji, Tadas Balčiūnas, Kiyoshi Ueda, Hans Jakob Wörner, "Attosecond circular-dichroism chronoscopy of photoelectron vortices", Nature Physics 19, 230-236 (2023)
[4] Meng Han*, Jia-Bao Ji, Kiyoshi Ueda, Hans Jakob Wörner, "Attosecond metrology in circular polarization", Optica 10, 1044-1052 (2023).
Imaging Molecular Dynamics with a Time-stamping Camera (Experimental)
E-mail: vinod@phys.ksu.edu
Ultrafast laser pulses enable us to measure the very rapid dynamics that molecules undergo after absorbing photons. A common step in imaging the internal motion of molecules is to ionize them and break them into charged fragments using very short pulses of laser light. As these fragments fly apart, their momenta carry information about the geometry of the molecule at the moment they were ionized. This project will involve setting up, testing and using a spectrometer and specialized camera that records the 3D momentum of each of the fragments. You will learn about pump-probe spectroscopy with femtosecond laser pulses, ion imaging spectrometers, ultrahigh vacuum systems and automated data acquisition. You will work with one or more graduate students and participate in an experimental run scheduled for late June/early July.
Studying Ultrafast Molecular Dynamics in Pump-probe Experiments with Femtosecond Lasers (Experimental)
E-mail: rolles@phys.ksu.edu
State-of-the-art femtosecond lasers can generate pulses with durations shorter than the time scales of fundamental molecular processes such as dissociation, rearrangement of molecular bonds, and vibrational motion. This can be exploited for creating “movies” of these processes in so-called pump-probe experiments. Here, the first (“pump”) laser pulse triggers the reaction of interest, and the second (“probe”) pulse, arriving after certain delay time, takes a snapshot of the molecular structure [1-3].
For the 2024 REU program, we offer a project focused on performing pump-probe experiments at the James R. Macdonald Laboratory using intense femtosecond laser pulses in the ultraviolet (UV) to near-infrared (NIR) spectral range. The main goal of these experiments will be to trace the time evolution of molecular reactions induced by either the UV or the NIR light pulse, primarily using a technique called ‘Coulomb explosion imaging’ [4-6]. Within the course of the project, the REU student will gain practical, hands-on experience working with ultrafast optics (in particular the characterization of femtosecond laser pulses), learn basics of laser interactions with atoms and molecules, get an introduction into electron and ion spectroscopy, and in the data acquisition and data analysis software for pump-probe experiments. The student will be co-mentored by Prof. Daniel Rolles and Prof. Artem Rudenko and work together with graduate students from the Rolles and Rudenko groups.
[1] F. Ziaee et al., Phys. Chem. Chem. Phys. 25, 9999 (2023).
[2] K. Borne et al., Nature Chemistry 16, 499-505 (2024).
[3] D. Rolles et al., Journal of Visualized Experiments 140, e57055 (2018).
[4] S. Bhattacharyya et al., J. Phys. Chem. Lett. 13, 5845 (2022).
[5] R. Boll et al., Nature Physics 18, 423-428 (2022).
[6] H.V.S Lam et al., Phys. Rev. Lett. 132, 123201 (2024).