# Research

**Research area:**

The advent of attosecond light sources has opened up the door to new possibilities in the study of the real-time electron dynamics in complex systems, and the direct observation and control of fundamental chemical processes. Thirty years after the femtochemistry revolution, we are witnessing the birth of attochemistry; a new field that allows us to explore and manipulate the rapid motion of electron in atoms and molecules. While femtochemistry provided the tools to follow nuclear motion during a chemical reaction, attochemistry will give us the possibility to obtain snapshots of a chemical reaction and to steer a nuclear motion via the control of the electron-density distribution. Since electrons in molecules are responsible for bond breaking and bond formation, control of their density opens the way to a new chemistry, where new compounds could be designed and unconventional reactions could become possible. The fundamental understanding of electron motion in molecules will lead to novel methods for energy transfer and energy release, impacting crucial fields, such as solar energy.

### Research objectives:

The main objective of my research is to develop efficient and versatile numerical methods to support experimental and theoretical studies of the interaction of multi-electron systems with ultra-short and intense laser pulses. These numerical tools are tailored to respond to the experimental needs and face the challenges of attosecond science. This research considers a variety of processes in atoms and molecules, such as high-order harmonic generation, vortex beams, strong-field ionization, time-resolved electron dynamics, electronic coherence, light-assisted electron and time-resolved x-ray scattering.

**Research grants:**

- National Science Foundation (NSF), Principal Investigator (PI), Attosecond and Strong Field Physics in Correlated Multielectron System, August 2020 -- July2023 ($138,092)
- XSEDE research allocation, Co-PI,
*Benchmark Calculations for Electron and Photon Collisions with Complex Atoms and Ions*

### Theoretical research group:

My research group at KSU is currently composed of two undergraduate students:

**Taylor Moon****Trevor Walsh**

**Recent publications:**

**2022:**

- K. Finger, D. Atri-Schuller, N. Douguet, K. Bartschat, and K. R. Hamilton, Phys. Rev. A 106 063113 (2022) High-order harmonic generation in the water window from mid-IR laser sources
- N. Douguet and K. Bartschat, Phys. Rev. A 106 053112 (2022) Photoelectron momen- tum distributions in the strong-field ionization of atomic hydrogen by few-cycle ellipti- cally polarized optical pulses
- B.P. Acharya, S. Dubey, K.L. Romans, A.H.N.C. De Silva, K. Foster, O. Russ, K. Bartschat, N. Douguet, D. Fischer, Phys. Rev. A 106 023113 (2022) Two-path interference in resonance-enhanced few-photon ionization of Li atoms
- E. V. Gryzlova, P. Carpeggiani, M. M. Popova, M. D. Kiselev, N. Douguet et al., Phys. Rev. Research 4 033231 (2022) Influence of an atomic resonance on the coherent control of the photoionization process

**2021:**

- N. Saito, N. Douguet, H. Sannohe, N. Ishii, T. Kanai, Y. Wu, A. Chew, S. Han, B. I. Schneider, J. Olsen,
L. Argenti, Z. Chang, and J. Itatani, Phys. Rev. Research
**3**043222 (2021) Attosecond electronic dynamics of core-excited states of N2O in the soft X-ray region - B. Ghomashi, N. Douguet, and L. Argenti, Phys. Rev. Lett.
**127**203201 (2021) Attosecond intramolecular scattering and vibronic delays - B. P. Acharya, M. Dodson, S. Dubey, K. L. Romans, A. H. N. C. De Silva, K. Foster,
O. Russ, K. Bartschat, N. Douguet, and D. Fischer, Phys. Rev. A
**104**053103 (2021) Magnetic dichroism in few-photon ionization of polarized atoms - A. De Silva, T. Moon, K.L. Romans, B.P. Acharya, S. Dubey, K. Foster, O. Russ, C. Rischbieter, N. Douguet, K. Bartschat, D. Fischer, Phys. Rev. A
**103**053125 (2021) Circular dichroism in atomic resonance-enhanced few-photon ionization - S. Meister, A. Bondy, K. Schnorr, S. Augustin, H. Lindenblatt, F. Trost, X. Xie, M.
Braune, R. Treusch, B. Manschwetus, N. Schirmel, H. Redlin, N. Douguet, T. Pfeifer, K. Bartschat, and R. Moshammer, Eur. Phys. J. D
**75**205 (2021) Linear dichroism in few-photon ionization of laser-dressed helium - H. Gharibnejad, N. Douguet, B. I. Schneider, J. Olsen, and L. Argenti, Comput. Phys. Commun.
**263**107889 (2021) A multi-center quadrature scheme for the molecular continuum - J. Fuchs, N. Douguet, S. Donsa, F. Martın, J. Burgdorfer, L. Argenti, L. Cattaneo, and U. Keller, Phys.
Rev. Research
**3**013195 (2021) Towards the complete phase profiling of attosecond wave packets - D. Bharti, D. Atri-Schuller, G. Menning, K. R. Hamilton, R. Moshammer, T. Pfeifer,
N. Douguet, K. Bartschat, and A. Harth, Phys. Rev. A
**103**022834 (2021) Decomposition of the transition phase in multi-sideband RABBITT schemes - A. De Silva, D. Atri-Schuller, S. Dubey, B.P. Acharya, K.L. Romans, K. Foster, O.
Russ, K. Compton, C. Rischbieter, N. Douguet, K. Bartschat, and D. Fischer, Phys. Rev. Lett.
**126**023201 (2021) Using circular dichroism to control energy transfer in multi-photon ionization

**2020:**

- S. Meister, A. Bondy, K. Schnorr, S. Augustin, H. Lindenblatt, F. Trost, X. Xie, M.
Braune, R. Treusch, N. Douguet, T. Pfeifer, K. Bartschat, and R. Moshammer, Phys. Rev. A
**102**062809 (2020) Photoelectron spectroscopy of laser-dressed atomic helium - T. Pauly, A. Bondy, K. R. Hamilton, N. Douguet, X.-M. Tong, D. Chetty, and K. Bartschat, Phys. Rev. A
**102**013116 (2020) Ellipticity Dependence of Excitation and Ionization of Argon Atoms by Short-Pulse Infrared Radiation - D. Chetty, R. D. Glover, B. A. deHarak, X.-M. Tong, H. Xu, T. Pauly, N. Smith, K.
R. Hamilton, K. Bartschat, J. P. Ziegel, N. Douguet, A. N. Luiten, P. S. Light, I. V. Litvinyuk, and R. T. Sang, Phys. Rev. A
**101**053402 (2020) Observation of Dynamic Stark Resonances in Strong-Field Excitation - N. Douguet, S. Fonseca dos Santos and T. N. Rescigno, Phys. Rev. A
**101**033411 (2020) Inner-shell photodetachment of C_{n}^{−}ions - J. Fuchs, N. Douguet, S. Donsa, F. Martın, J. Burgdorfer, L. Argenti, L. Cattaneo, and U. Keller, Optica
**7**154 (2020) Time delays from one-photon transitions in the continuum

**2019:**

- E. V. Gryzlova, M. M. Popova, A. N. Grum-Grzhimailo, E. I. Staroselskaya, N. Douguet, and K. Bartschat, Phys. Rev. A
**100**063417 (2019) Coherent control of the photoelec- tron angular distribution in ionization of neon by a circularly polarized bichromatic field in the resonance region - Z. Mezei, K. Chakrabarti, M. Epee Epee, O. Motapon, Y. Chi, A. Mehdi, N. Douguet, S. Fonseca dos Santos, V. Kokoouline, and I. Schneider, ACS Earth Space Chem
**3**2376 (2019) Electron-induced excitation, recombination and dissociation of molecular ions initiating the formation of complex organic molecules - S. Donsa, N. Douguet, J. Burgdorfer, I. Brezinova , and L. Argenti, Phys. Rev. Lett.
**123**, 133203 (2019) Circular holographic ionization-phase meter - A. N. Grum-Grzhimailo, N. Douguet, M. Meyer, and K. Bartschat, Phys. Rev. A
**100**033404 (2019) Two-color XUV+NIR multi-photon near-threshold ionization of the helium ion by circularly polarized light in the region of the 3p resonance - U. Satya Sainadh, H. Xu, X. Wang, A.-T. Noor, W. C. Wallace, N. Douguet, A. W. Bray, I. Ivanov, K. Bartschat, A. Kheifets, R. T. Sang, and I. V. Litvinyuk,
Nature
**567**75 (2019) Attosecond angular streaking and tunnelling time in atomic hydrogen - C. H. Yuen, N. Douguet, S. Fonseca dos Santos, A. E. Orel, and V. Kokoouline, Phys. Rev. A
**99**032701 (2019) Simplified model to treat the electron attachment of complex molecules: Application to H2CN and the quest for CN− formation mechanism - B. Ghomashi, N. Douguet, and L. Argenti, Phys. Rev. A
**99**053407 (2019), Resonant anisotropic emission in RABBITT spectroscopy - A. Harth, N. Douguet, K. Bartschat, R. Moshammer, and T. Pfeifer, Phys. Rev. A
**99**0233410 (2019) Extracting phase information of continuum-continuum dipole transitions - N. Douguet and K. Bartschat, Phys. Rev. A
**99**023417 (2019) Attoclock setup with negative ions: A possibility for experimental validation