Real-time observation of electronic, vibrational, and rotational dynamics in nitric oxide with attosecond soft x-ray pulses at 400  eV

Saito, Nariyuki; Sannohe, Hiroki; Ishii, Nobuhisa; Kanai, Teruto; Kosugi, Nobuhiro; Wu, Yi; Chew, Andrew; Han, Seunghwoi; Chang, Zenghu; Itatani, Jiro

doi:10.1364/optica.6.001542

Cited by 88 publications

(50 citation statements)

References 37 publications

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“…The demonstration of the increased photon flux using a short SWIR wavelength and a long HHG medium represents an important step towards the observation of attosecond dynamics in solution phase with transient absorption in the water window 55 . The dual-wavelength approach furthermore allows the strong-field excitation of molecules 4,34,38 or single-photon pumping across a majority of semiconductor bandgaps 8,9 , including 2D semiconductors 56 . The broadband, few-cycle vis-NIR pulse could additionally be upconverted to few-fs tunable UV pulses 57 , opening new possibilities for the study of ultrafast excited-state dynamics in molecules [58][59][60] .…”

Section: Discussionmentioning

confidence: 99%

“…Due to the smaller photon energy in the SWIR, using a similar approach for SXR transient absorption considerably reduces the pumping excitation capabilities. Note however that field-driven carrier motion in a semi-metal 33 and tunnel ionization of a low ionization potential molecule 34 with > 1600 nm few-cycle pulses have recently been observed.…”

Section: Introductionmentioning

confidence: 99%

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Efficient table-top dual-wavelength beamline for ultrafast transient absorption spectroscopy in the soft X-ray region

Barreau

Ross

Garg

et al. 2020

Sci Rep

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We present a table-top beamline providing a soft X-ray supercontinuum extending up to 350 eV from high-order harmonic generation with sub-13 fs 1300 nm driving pulses and simultaneous production of sub-5 fs pulses centered at 800 nm. Optimization of the high harmonic generation in a long and dense gas medium yields a photon flux of ~2 x 10 7 photons/s/1% bandwidth at 300 eV. The temporal resolution of X-ray transient absorption experiments with this beamline is measured to be 11 fs for 800 nm excitation. This dual-wavelength approach, combined with high flux and high spectral and temporal resolution soft X-ray absorption spectroscopy, is a new route to the study of ultrafast electronic dynamics in carbon-containing molecules and materials at the carbon K-edge. 2/10 Description of the table-top dual-wavelength beamlineThe beamline is summarized in Figure 1. It uses a 13 mJ , 800 nm, 30 fs, 1 kHz Ti:Sapphire laser (Coherent Legend Elite Duo), whose energy is split into 11 mJ +2 mJ to produce the probe and pump pulses, respectively, used in time-resolved X-ray transient absorption experiments. This section details the simultaneous compression of SWIR (centered at 1300 nm or 1400 nm) and visible-near infrared (centered at 800 nm) pulses, and the characteristics of the soft X-ray spectrometer. Production of few-cycle short-wave infrared pulsesThe few-cycle pulses centered at 1300 nm in the SWIR are produced using an OPA followed by spectral broadening in a hollow-core fiber filled with a rare gas 35 and compression with chirped mirrors 36 . The 11 mJ 800 nm beam is further split into 0.5 mJ and 10.5 mJ for use in a two-stage OPA, which converts the 800 nm to SWIR (1300 nm). The two-stage system is obtained from Light Conversion and is designed to provide CEP stability of the signal pulses. The first stage is a low energy OPA (TOPAS Prime), pumped by 0.5 mJ, which provides 90 J of 2 m pulses in the idler. Due to the parametric amplification process, the idler pulses are passively CEP stabilized, with a stability of <200 mrad. They are then used as the seed for the white light generation in a second, high energy, OPA (HE-TOPAS) pumped with the remaining 10.5 mJ of 800 nm light. This design should ensure the CEP stability of the signal pulses over the 1200-1600 nm tunable range of the OPA, regardless of the CEP stability of the pump laser. However, the following results are obtained with a CEP-averaged signal pulse. The 2.8 mJ, 1300 nm, 40 fs output is focused with a 2-m focusing mirror to a focal size of 390 m (at 1/e 2 ) at the entrance of a 3-m-long, 700-m-inner diameter stretched hollow-core fiber (HCF) filled with 0.4 bar of argon (Few-Cycle Inc.). The ratio of beam

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Efficient table-top dual-wavelength beamline for ultrafast transient absorption spectroscopy in the soft X-ray region

Barreau

Ross

Garg

et al. 2020

Sci Rep

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“…Attosecond water window X-ray sources have recently enabled the observation of electronic processes in Ar atom at the L-edge (~250 eV) 63 , and in TiS 2 films at the Ti L-edge (~460 eV) 64 . Ionization, vibration, and rotation dynamics have been resolved in NO molecules using attosecond transient-absorption spectroscopy at the Nitrogen K-edge (~400 eV) 65 , as shown in Fig. 2.…”

Section: Applications Of Attosecond X-ray Sourcesmentioning

confidence: 99%

Attosecond science based on high harmonic generation from gases and solids

Li¹,

Lu²,

Chew³

et al. 2020

Nat Commun

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242

126

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Recent progress in high power ultrafast shortwave and mid-wave infrared lasers has enabled gas-phase high harmonic generation (HHG) in the water window and beyond, as well as the demonstration of HHG in condensed matter. In this Perspective, we discuss the recent advancements and future trends in generating and characterizing soft X-ray pulses from gasphase HHG and extreme ultraviolet (XUV) pulses from solid-state HHG. Then, we discuss their current and potential usage in time-resolved study of electron and nuclear dynamics in atomic, molecular and condensed matters. T abletop attosecond light sources in the soft X-ray (SXR) spectral region based on highharmonic generation are highly desirable in chemical and material sciences since they can spectroscopically identify specific elements, as well as the oxidation states, charge states and even the spin states of those elements 1. One of the important spectral regions is the "water window" (282-533 eV), which covers the atomic K-shell excitation of carbon and oxygen. Although high harmonics in the water window were first generated with Ti:Sapphire lasers centered at 800 nm more than 20 years ago 2,3 , the X-ray photon flux was too low for timeresolved applications. The mechanism of HHG in gases can be explained by the semiclassical three-step model 4-6. When driving laser-field strength reaches~10 8 V m −1 , the bound electron in the atomic gas can tunnel through the Coulomb potential barrier and become a free electron. In the oscillating laser field, the free-electron wave packet may return to its parent ion with the right time of birth. At recombination, the interference between the wave packets of the returning and bound electrons produces an oscillating dipole that emits attosecond radiation. Returning electrons with various kinetic energy will recombine at different times giving rise to the chirp in the attosecond radiation 7. This process repeats twice for every optical cycle. The temporal beating of attosecond pulses results in the high-harmonic combs in the spectral domain. Empowered by the advances in driving lasers with center wavelengths around 1.8 μm, soft X-ray high harmonics can be generated with a moderate intensity of 10 14 W cm −2 (see Box 1 for details). Significant progress has recently been made in developing attosecond light within the water window 8. By spectrally broadening pulses from an Optical Parametric Amplifier (OPA) using a gas-filled hollow-core fiber 9 or by broadband phase matching in an Optical Parametric Chirped Pulse Amplifier (OPCPA) 10 , two-cycle, mJ-level pulses centered with 1 kHz repetition

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“…Time-resolved NEXAFS in the soft X-ray region, especially above the carbon K-edge energy, is a promising tool and would enable the investigation of ultrafast structural, electron, and spin dynamics. Femtosecond time-resolved soft X-ray absorption spectroscopy by this HHG technology has been performed, and the photodissociation processes of CF 4 [19] and NO [20] molecules were observed. However, at present, usable light intensity can only be obtained for energies of up to about 400 eV (nitrogen absorption edge) [21].…”

Section: Introductionmentioning

confidence: 99%

Demonstration of Transmission Mode Soft X-ray NEXAFS Using Third- and Fifth-Order Harmonics of FEL Radiation at SACLA BL1

et al. 2020

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We demonstrate the applicability of third- and fifth-order harmonics of free-electron laser (FEL) radiation for soft X-ray absorption spectroscopy in the transmission mode at SACLA BL1, which covers a photon energy range of 20 to 150 eV in the fundamental FEL radiation. By using the third- and fifth-order harmonics of the FEL radiation, we successfully recorded near-edge X-ray absorption fine structure (NEXAFS) spectra for Ar 2p core ionization and CO2 C 1s and O 1s core ionizations. Our results show that the utilization of third- and fifth-order harmonics can significantly extend the available photon energies for NEXAFS spectroscopy using an FEL and opens the door to femtosecond pump-probe NEXAFS using a soft X-ray FEL.

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Real-time observation of electronic, vibrational, and rotational dynamics in nitric oxide with attosecond soft x-ray pulses at 400 eV

Cited by 88 publications

References 37 publications

Efficient table-top dual-wavelength beamline for ultrafast transient absorption spectroscopy in the soft X-ray region

Efficient table-top dual-wavelength beamline for ultrafast transient absorption spectroscopy in the soft X-ray region

Attosecond science based on high harmonic generation from gases and solids

Demonstration of Transmission Mode Soft X-ray NEXAFS Using Third- and Fifth-Order Harmonics of FEL Radiation at SACLA BL1

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