Photoionic states of organic molecules studied by HeI photoelectron spectroscopy

Kimura, Ko; Achiba, Yohji; Katsumata, Shunji; Yamazaki, T.; Iwata, Suehiro

doi:10.1016/0047-2670(81)85305-1

Cited by 68 publications

(94 citation statements)

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“…Photoemission spectrum of (a) azulene and (b) benzonitrile. Experimental results are obtained from (a) ref and (b) ref . The rightmost peak in the experimental spectrum corresponds to the electron affinity (EA), and it is broadened by a Gaussian function with a width of 0.2 eV around experimental EA value.…”

Section: Resultsmentioning

confidence: 99%

Approximating Quasiparticle and Excitation Energies from Ground State Generalized Kohn–Sham Calculations

Mei

et al. 2018

J. Phys. Chem. A

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Quasiparticle energies and fundamental band gaps in particular are critical properties of molecules and materials. It was rigorously established that the generalized Kohn-Sham HOMO and LUMO orbital energies are the chemical potentials of electron removal and addition and thus good approximations to band edges and fundamental gaps from a density functional approximation (DFA) with minimal delocalization error. For other quasiparticle energies, their connection to the generalized Kohn-Sham orbital energies has not been established but remains highly interesting. We provide the comparison of experimental quasiparticle energies for many finite systems with calculations from the GW Green's function and localized orbitals scaling correction (LOSC), a recently developed correction to semilocal DFAs, which has minimal delocalization error. Extensive results with over forty systems clearly show that LOSC orbital energies achieve slightly better accuracy than the GW calculations with little dependence on the semilocal DFA, supporting the use of LOSC DFA orbital energies to predict quasiparticle energies. This also leads to the calculations of excitation energies of the N -electron systems from the ground state DFA calculations of the (N − 1)-electron systems. Results show good performance with accuracy similar to TDDFT and the delta SCF approach for valence excitations with commonly used DFAs with or without LOSC. For Rydberg states, good accuracy was obtained only with the use of LOSC DFA. This work highlights the pathway to quasiparticle and excitation energies from ground density functional calculations. 2Graphical TOC EntryQuasiparticles are a powerful concept in electronic structure theory of many-electron systems. In particular, accurate prediction of quasiparticle energies is essential for interpreting the electronic excitation spectra of molecules and materials, such as photoemission and optical experiments. Formally, quasiparticle energies can be exactly formulated in many-body perturbation theory. 1-3 In practice, the GW approximation 4-7 is most widely used for bulk simulations. Unfortunately, GW calculations are still expensive computationally. Therefore, a low-cost alternative to GW approximation that offers good accuracy for the prediction of quasiparticle energies is critical to the calculations of large-scale systems, and for efficient high throughput study of materials.Kohn-Sham (KS) density functional theory (DFT), 8-10 due to its good balance between accuracy and computational tractability, is among the most popular and versatile methods available for many-electron problems. In addition to the total electron energy, the physical interpretation of the KS eigenvalues has also attracted great interest. It has been known for decades that among the KS eigenvalues obtained from the exact functional, the highest occupied molecular orbital (HOMO) energy, ε HOMO , is negative vertical ionization potential (VIP), −I. [10][11][12][13][14][15][16][17] In 2008, it was rigorously proven 18,19 that within the generaliz...

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Section: Resultsmentioning

confidence: 99%

Approximating Quasiparticle and Excitation Energies from Ground State Generalized Kohn–Sham Calculations

Mei

et al. 2018

J. Phys. Chem. A

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“…Henderson 44 – which are absent or strongly attenuated in the spectrum of dry NPs. Water peak assignment was based on Kimura’s et al 45 valence states study. The presence of molecular water states in the valence band region (blue spectrum) is assigned to the atomization procedure of NPs in water suspension.…”

Section: Resultsmentioning

confidence: 99%

Water adsorption on TiO2 surfaces probed by soft X-ray spectroscopies: bulk materials vs. isolated nanoparticles

Benkoula¹,

Sublemontier²,

Patanen³

et al. 2015

Sci Rep

116

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We describe an experimental method to probe the adsorption of water at the surface of isolated, substrate-free TiO2 nanoparticles (NPs) based on soft X-ray spectroscopy in the gas phase using synchrotron radiation. To understand the interfacial properties between water and TiO2 surface, a water shell was adsorbed at the surface of TiO2 NPs. We used two different ways to control the hydration level of the NPs: in the first scheme, initially solvated NPs were dried and in the second one, dry NPs generated thanks to a commercial aerosol generator were exposed to water vapor. XPS was used to identify the signature of the water layer shell on the surface of the free TiO2 NPs and made it possible to follow the evolution of their hydration state. The results obtained allow the establishment of a qualitative determination of isolated NPs’ surface states, as well as to unravel water adsorption mechanisms. This method appears to be a unique approach to investigate the interface between an isolated nano-object and a solvent over-layer, paving the way towards new investigation methods in heterogeneous catalysis on nanomaterials.

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“…Considering the pulse intensities employed in the experiment (≲5×1013normalW/normalcnormalmnormal2 and wavelengths of 1,800/900 nm), strong-field ionization from the Q0+3 state populates mainly the ground (trueX~+, split into two spin-orbit components with vertical ionization potentials Inormalp of ≈9.13 and ≈9.68 eV) and the first excited (Ã+, Inormalp≈11.08 eV) states (49, 50). Neglecting the spin-orbit interaction in the cationic states, this gives rise to in total four channels contributing to the HHG process.…”

Section: Discussionmentioning

confidence: 99%

Real-time probing of chirality during a chemical reaction

Baykusheva

Zindel

Svoboda

et al. 2019

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

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Chiral molecules interact and react differently with other chiral objects, depending on their handedness. Therefore, it is essential to understand and ultimately control the evolution of molecular chirality during chemical reactions. Although highly sophisticated techniques for the controlled synthesis of chiral molecules have been developed, the observation of chirality on the natural femtosecond time scale of a chemical reaction has so far remained out of reach for isolated molecules.Here, we demonstrate a general experimental technique, based on high-harmonic generation in tailored laser fields, and apply it to probe the time evolution of molecular chirality during the photodissociation of 2-iodobutane. These measurements show a change in sign and a pronounced increase in the magnitude of the chiral response over the first 100 fs, followed by its decay within less than 500 fs, revealing the photodissociation to achiral products. The observed time evolution is explained in terms of the variation of the electric and magnetic transition-dipole moments between the lowest electronic states of the cation as a function of the reaction coordinate. These results open the path to investigations of the chirality of molecular reaction pathways, light-induced chirality in chemical processes and the control of molecular chirality through tailored laser pulses. SIGNIFICANCE STATEMENTChiral molecules interact and react differently, depending on their handedness (left vs. right). This chiral recognition is the basic principle governing most biomolecular interactions, such as the activity of drugs or our perception of scents. Inspite of this fundamental importance, a real-time (femtosecond) observation of chirality during a chemical reaction has remained out of reach for isolated molecules. In the present work, we report this fundamental breakthrough with a seemingly unlikely technique: high-harmonic generation (HHG) in tailored intense near-infrared laser fields. Combining the powerful transient-grating technique with HHG in counter-rotating circularly-polarized laser fields, we follow the temporal evolution of molecular chirality during a chemical reaction from the unexcited electronic ground state through the transition-state region to the final achiral products.

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Photoionic states of organic molecules studied by HeI photoelectron spectroscopy

Cited by 68 publications

References 0 publications

Approximating Quasiparticle and Excitation Energies from Ground State Generalized Kohn–Sham Calculations

Approximating Quasiparticle and Excitation Energies from Ground State Generalized Kohn–Sham Calculations

Water adsorption on TiO2 surfaces probed by soft X-ray spectroscopies: bulk materials vs. isolated nanoparticles

Real-time probing of chirality during a chemical reaction

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