Coherent excitation of vibrational wave functions observed in core hole decay spectra of O2, N2 and CO

Neeb, M.; Rubensson, Jan‐Erik; Biermann, Mark L.; Eberhardt, W.

doi:10.1016/0368-2048(93)02050-v

Cited by 178 publications

(112 citation statements)

References 27 publications

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“…(4) coincides with conventional C1s → π * absorption spectroscopy [51]. The negative parts in the spectra around 287.2 eV mainly come from the emissions |ν = 1 R → |ν = 1 I .…”

Section: Numerical Resultssupporting

confidence: 81%

Nonlinear resonant Auger spectroscopy in CO using an x-ray pump-control scheme

2016

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In the present paper we propose nonlinear femtosecond x-ray pump-probe spectroscopy to study the vibrational dynamics of a core-excited molecular state and discuss numerical results in CO. A femtosecond pump resonantly excites the carbon core-excited 1s-1π * state of the CO molecule. A second strong probe (control) pulse is applied at variable delay and is resonantly coupled to a valence excited state of the molecule. The strong nonlinear coupling of the control pulse induces Rabi flopping between the two electronic states. During this process, a vibrational wave packet in the core-excited state is created, which can be effectively manipulated by changing the time delay between pump and control pulses. We present an analysis of the resonant Auger electron spectrum and the transient absorption or emission spectrum on the pump transition and discuss their information content for reconstruction of the vibrational wave packet.

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“…(4) coincides with conventional C1s → π * absorption spectroscopy [51]. The negative parts in the spectra around 287.2 eV mainly come from the emissions |ν = 1 R → |ν = 1 I .…”

Section: Numerical Resultssupporting

confidence: 81%

Nonlinear resonant Auger spectroscopy in CO using an x-ray pump-control scheme

2016

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“…Although the valence electrons are delocalized in a condensed phase, the involvement of the core level makes both XRS and XES very local probes of the electronic structure (23). Furthermore, the attosecond time scale of the XRS excitation process and the O 1s life time of Ϸ4 fs in XES (24) are much shorter than the 1-2 ps typical for H-bond dynamics (25).…”

Section: Figurementioning

confidence: 99%

The inhomogeneous structure of water at ambient conditions

Huang

Wikfeldt

Tokushima

et al. 2009

Proc. Natl. Acad. Sci. U.S.A.

556

610

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Small-angle X-ray scattering (SAXS) is used to demonstrate the presence of density fluctuations in ambient water on a physical length-scale of Ϸ1 nm; this is retained with decreasing temperature while the magnitude is enhanced. In contrast, the magnitude of fluctuations in a normal liquid, such as CCl4, exhibits no enhancement with decreasing temperature, as is also the case for water from molecular dynamics simulations under ambient conditions. Based on X-ray emission spectroscopy and X-ray Raman scattering data we propose that the density difference contrast in SAXS is due to fluctuations between tetrahedral-like and hydrogen-bond distorted structures related to, respectively, low and high density water. We combine our experimental observations to propose a model of water as a temperature-dependent, fluctuating equilibrium between the two types of local structures driven by incommensurate requirements for minimizing enthalpy (strong near-tetrahedral hydrogen-bonds) and maximizing entropy (nondirectional H-bonds and disorder). The present results provide experimental evidence that the extreme differences anticipated in the hydrogen-bonding environment in the deeply supercooled regime surprisingly remain in bulk water even at conditions ranging from ambient up to close to the boiling point.density fluctuations ͉ liquid-liquid hypothesis ͉ small angle X-ray scattering ͉ water structure ͉ X-ray spectroscopy L iquid water shows many anomalies in its thermodynamic properties such as compressibility, density variation and heat capacity (1-4). In the low-temperature regime, below the freezing point, these properties deviate strongly from normal and theories, related to a liquid-liquid phase transition between high and low density water, have been proposed to account for these anomalies (5). Although the anomalies are extreme in the supercooled region they are also present at ambient conditions where most of waters' physical, chemical and biological processes of importance occur. In contrast, water at ambient conditions has traditionally been considered as a homogeneous distribution of near-tetrahedral hydrogen-bonded (H-bonded) structures with thermal fluctuations increasing with temperature. This picture has been challenged by recent studies based on X-ray Raman (XRS) and conventional X-ray absorption spectroscopy (XAS) (6), and X-ray emission spectroscopy (XES) (7), suggesting two distinct local structures with tetrahedral as a minority and a highly hydrogen-bond (H-bond) distorted asymmetrical as the majority. In particular the proposed predominant asymmetrical structure has caused intense debate in the last years (see refs. 7 and 8 for detailed discussion).SAXS and small-angle neutron scattering (SANS) provide the most direct probes of density variations or fluctuations on large length scales in a liquid. Through an enhancement of the structure factor at low momentum transfer, Q, small deviations from the average electron density at different length scales can be reliably identified (9). Previous SAXS studies of w...

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“…Since then, it was experimentally identified in several experiments like e.g. the first C1s → π * resonant Auger spectrum for CO, excited by narrow monochromator bandwidth synchrotron radiation, where it gave rise to modulations of the final state vibrational intensity distributions which could not be explained by a simple FranckCondon two-step excitation-deexcitation picture [16]. A more recent study of LVI can be found, for instance, in Ref.…”

Section: Interference Phenomenamentioning

confidence: 99%

“…[18] and references therein). Furthermore, the vibrational intensity distribution in the final state may vary strongly upon tuning of the excitation energy across the intermediate resonance state [16,19]. Fig.…”

Section: Interference Phenomenamentioning

confidence: 99%

Core-level spectroscopy and dynamics of free molecules

Feifel¹,

Piancastelli²

2011

Journal of Electron Spectroscopy and Related Phenomena

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A review of recent results on spectroscopy and dynamics of free molecules is presented. The experimental research reported here is mainly concerned with processes of core excitation and decay of isolated molecules, primarily investigated by resonant Auger spectroscopy. Several examples are shown concerning the interplay of the timescales of electron decay with nuclear motion involving dissociation processes, the occurrence of interference phenomena and recoil. The capability of such studies to reveal subtle details of the light-matter interaction, of the electronic structure and of the evolution of the short-lived states thus created is enlightened.

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Coherent excitation of vibrational wave functions observed in core hole decay spectra of O2, N2 and CO

Cited by 178 publications

References 27 publications

Nonlinear resonant Auger spectroscopy in CO using an x-ray pump-control scheme

Nonlinear resonant Auger spectroscopy in CO using an x-ray pump-control scheme

The inhomogeneous structure of water at ambient conditions

Core-level spectroscopy and dynamics of free molecules

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