A5015090131- Laser-Matter Interactions and Applications
- Mass Spectrometry Techniques and Applications
- Advanced Chemical Physics Studies
- Spectroscopy and Quantum Chemical Studies
- Advanced Fiber Laser Technologies
- Atomic and Molecular Physics
- Laser Design and Applications
- Molecular spectroscopy and chirality
- Laser-induced spectroscopy and plasma
- Particle Accelerators and Free-Electron Lasers
- DNA and Nucleic Acid Chemistry
- Advanced Optical Sensing Technologies
- Spectroscopy and Laser Applications
- Random lasers and scattering media
- Photochemistry and Electron Transfer Studies
- Optical Coherence Tomography Applications
- Biochemical Analysis and Sensing Techniques
- Ion-surface interactions and analysis
- Photocathodes and Microchannel Plates
- Laser-Plasma Interactions and Diagnostics
- Laser Material Processing Techniques
- Free Radicals and Antioxidants
- Calibration and Measurement Techniques
- Cold Atom Physics and Bose-Einstein Condensates
- Force Microscopy Techniques and Applications
Max-Born-Institute for Nonlinear Optics and Short Pulse Spectroscopy
2020-2023
Heriot-Watt University
2015-2023
University of Glasgow
2019
Griffith University
2013-2016
Quantum (Australia)
2013-2016
ARC Centre of Excellence for Coherent X-ray Science
2013-2016
Australian Research Council
2013-2016
Institute for Atomic and Molecular Physics
2006-2013
We present an interferometric pump-probe technique for the characterization of attosecond electron wave packets (WPs) that uses a free WP as reference to measure bound WP. demonstrate our method by exciting helium atoms using pulse (AP) with bandwidth centered near ionization threshold, thus creating both and simultaneously. After variable delay, is ionized few-cycle infrared laser precisely synchronized original AP. By measuring delay-dependent photoelectron spectrum we obtain interferogram...
We present a combined theoretical and experimental study of ultrafast wave-packet dynamics in the dissociative ionization H_{2} molecules as result irradiation with an extreme-ultraviolet (XUV) pulse followed by infrared (IR) pulse. In experiments where duration both XUV IR pulses are shorter than vibrational period H_{2};{+}, dephasing rephasing wave packet that is formed H_{2};{+} upon neutral molecule observed. exceeds (15 fs), pronounced dependence H;{+} kinetic energy distribution on...
We present the design of a velocity map imaging spectrometer where target gas is injected from capillary that integrated in repeller plate ion optics assembly drives electrons/ions formed by ionization or dissociation to two-dimensional detector. The geometry this allows use densities interaction region are two three orders magnitude higher than used standard spectrometers, making detector suitable for working with weak light sources such as newly developed attosecond pulse sources,...
De-excitation of DNA nucleosides on picosecond timescales was measured and found to be twice as fast the equivalent nucleobases.
We present an initial demonstration of a velocity-map imaging (VMI) experiment using back-irradiation laser-based desorption source directly integrated into the electrode assembly. This has potential to greatly expand utility popular VMI approach by permitting its use with high density plumes non-volatile molecular samples. Photoelectron circular dichroism measurements on phenylalanine molecule 400 nm multiphoton ionization are used illustrate this novel method, revealing forward-backward...
High-order harmonic generation (HHG) normally requires a careful adjustment of the driving laser intensity (typically ${10}^{14}--{10}^{15}$ W/${\mathrm{cm}}^{2}$) and gas medium parameters to obtain microscopically macroscopically optimized output. In contrast conventional wisdom, we present experimental results indicating efficient HHG in all rare gases, using high-density around ${10}^{16}$ W/${\mathrm{cm}}^{2}$. The are corroborated by theoretical simulations, which indicate that...
Wavelength-dependent measurements of the RNA base uracil, undertaken with nanosecond ultraviolet laser pulses, have previously identified a fragment at m/z = 84 (corresponding to C3H4N2O+ ion) excitation wavelengths ≤232 nm. This has been interpreted as possible signature theoretically predicted ultrafast ring-opening occurring on neutral excited state potential energy surface. To further investigate dynamics this mechanism, and also non-adiabatic operating more generally in we used newly...
Ionization of atoms and molecules in strong laser fields is a fundamental process many research, especially the emerging field attosecond science. So far, demonstrably accurate data have only been acquired for atomic hydrogen (H), species that accessible to few investigators. Here, we present measurements ionization yield argon, krypton, xenon with percent-level accuracy, calibrated using H, regime widely used We derive transferable calibration standard peak intensity, 1.3%, based on simple...
The ongoing development of intense high-harmonic generation (HHG) sources has recently enabled highly nonlinear ionization atoms by the absorption at least 10 extreme-ultraviolet (XUV) photons within a single atom [Senfftleben \textit{et al.}, arXiv1911.01375]. Here we investigate role that reshaping fundamental, few-cycle, near-infrared (NIR) driving laser 30-cm-long HHG Xe medium plays in pulses. Using an incident NIR intensity is higher than what required for phase-matched HHG, signatures...
We present a theoretical investigation of the impulsive orientation that can be induced by exposing sample state-selected NO molecules to combination dc field and short laser pulse. A strong degree laser-field-free alignment is already achievable at moderate intensities further improved tailoring temporal profile The are only limited maximum value applied pulse energy in femtosecond Using an evolutionary algorithm coupled non-perturbative calculation time-dependent Schrödinger equation,...
Recent experiments in ultrafast physics have established the importance of above-threshold ionization (ATI) measuring and controlling carrier-envelope phase (CEP) few-cycle laser pulses. We performed an investigation atomic hydrogen subjected to intense CEP-stable The experimental ATI spectra been compared predictions from ab initio numerical solution time-dependent Schrödinger equation three dimensions. Good agreement between experiment theory has achieved without using any free fit...
Ionization mechanisms of C${}_{60}$ molecules irradiated by a short intense 800-nm laser pulse are studied. Angle-resolved photoelectron spectra show above-threshold ionization (ATI) patterns with low peak contrast and remarkably smooth angular distribution. The results interpreted combining two theoretical models. A time-dependent Schr\"odinger equation (TDSE) calculation based on the $B$-spline method that explicitly takes into account molecular potential mimics single-active-electron...
We report time-resolved photoelectron imaging studies of gas-phase pyrrole over the 267-240 nm excitation region, recorded in conjunction with a 300 probe. Of specific interest is lowest-lying (3s/πσ*) state, which exhibits very weak oscillator strength but thought to be excited directly at wavelengths ≤254 nm. conclude, however, that only significant contribution our data all investigated from non-resonant ionization. Our findings do not rule out state (as appears confirmed by supporting...
Photoelectron angular distributions (PADs) produced from the photoionization of chiral molecules using elliptically polarized light exhibit a forward/backward asymmetry with respect to optical propagation direction. By recording these velocity-map imaging (VMI) technique, resulting photoelectron elliptical dichroism (PEELD) has previously been demonstrated as promising spectroscopic tool for studying in gas phase. The use laser pulses, however, produces PADs (and consequently, PEELD...
Abstract We present experiments on field-free molecular alignment of N2 and CO2 probed with short XUV pulses that are obtained via high-harmonic generation. The induce a dissociative ionization or Coulomb explosion the molecule, where fragment ion recoil (measured using velocity map imaging technique) provides information parent molecule at time ionization. discuss how photoelectron detection may in future allow determination molecular-frame angular distributions structure. Acknowledgements...
Laser-based thermal desorption facilitates the first gas-phase study of ultrafast non-adiabatic dynamics operating in 5,6-dihydroxyinole following ultraviolet excitation.
High-lying Rydberg states of Xe have been ionized using intense $108\text{ }\ensuremath{\mu}\text{m}$ radiation from a free-electron laser. Measured two-dimensional photoelectron images reveal significant above-threshold ionization and contain an indirect contribution resulting the combined action atomic Coulomb field, laser dc electric field spectrometer on electron. The observation contains information about electron localization directly after excitation indicates that experiments are...
Non-line-of-sight (NLOS) imaging relies on collecting light that is rendered incoherent from the multiple scattering events and then post-processed to provide an estimate of hidden scene. Here we employ coherent phase control outgoing laser beam front so as refocus behind obscuring obstacle use speckle memory effect scan focused spot across The back-reflected intensity provides a direct measurement scene with signal-to-noise ratio greatly improved when measured using temporally gated...
We present experimental and numerical studies on control of rotational population transfer NO($J=1/2$) molecules to higher states. are able 57$%$ the $J=5/2$ state 46$%$ $J=9/2$, in good agreement with quantum mechanical simulations. The optimal pulse shapes composed sequences delays corresponding beat frequencies states ladder. evolutionary algorithm is limited by constraints such as volume averaging finite laser intensity used, latter circumvent ionization. Without these constraints,...