TY - JOUR AB - We show that bimolecular reactions between species confined to the surfaces of nanoparticles can be manipulated by the nature of the linker, as well as by the curvature of the underlying particles. AU - Zdobinsky, Tino AU - Sankar Maiti, Pradipta AU - Klajn, Rafal ID - 13403 IS - 7 JF - Journal of the American Chemical Society KW - Colloid and Surface Chemistry KW - Biochemistry KW - General Chemistry KW - Catalysis SN - 0002-7863 TI - Support curvature and conformational freedom control chemical reactivity of immobilized species VL - 136 ER - TY - JOUR AB - The sensitivities of high-harmonic generation (HHG) and strong-field ionization (SFI) to coupled electronic and nuclear dynamics are studied, using the nitric oxide (NO) molecule as an example. A coherent superposition of electronic and rotational states of NO is prepared by impulsive stimulated Raman scattering and probed by simultaneous detection of HHG and SFI yields. We observe a fourfold higher sensitivity of high-harmonic generation to electronic dynamics and attribute it to the presence of inelastic quantum paths connecting coherently related electronic states [Kraus et al., Phys. Rev. Lett.111, 243005 (2013)]. Whereas different harmonic orders display very different sensitivities to rotational or electronic dynamics, strong-field ionization is found to be most sensitive to electronic motion. We introduce a general theoretical formalism for high-harmonic generation from coupled nuclear-electronic wave packets. We show that the unequal sensitivities of different harmonic orders to electronic or rotational dynamics result from the angle dependence of the photorecombination matrix elements which encode several autoionizing and shape resonances in the photoionization continuum of NO. We further study the dependence of rotational and electronic coherences on the intensity of the excitation pulse and support the observations with calculations. AU - Baykusheva, Denitsa Rangelova AU - Kraus, Peter M. AU - Zhang, Song Bin AU - Rohringer, Nina AU - Wörner, Hans Jakob ID - 14018 JF - Faraday Discussions KW - Physical and Theoretical Chemistry SN - 1359-6640 TI - The sensitivities of high-harmonic generation and strong-field ionization to coupled electronic and nuclear dynamics VL - 171 ER - TY - JOUR AB - The cyclopropene radical cation (c-C3H₄⁺) is an important but poorly characterized three-membered-ring hydrocarbon. We report on a measurement of the high-resolution photoelectron and photoionization spectra of cyclopropene and several deuterated isotopomers, from which we have determined the rovibrational energy level structure of the X⁺ (2)B2 ground electronic state of c-C3H₄⁺ at low energies for the first time. The synthesis of the partially deuterated isotopomers always resulted in mixtures of several isotopomers, differing in their number of D atoms and in the location of these atoms, so that the photoelectron spectra of deuterated samples are superpositions of the spectra of several isotopomers. The rotationally resolved spectra indicate a C(2v)-symmetric R0 structure for the ground electronic state of c-C3H₄⁺. Two vibrational modes of c-C3H₄⁺ are found to have vibrational wave numbers below 300 cm(-1), which is surprising for such a small cyclic hydrocarbon. The analysis of the isotopic shifts of the vibrational levels enabled the assignment of the lowest-frequency mode (fundamental wave number of ≈110 cm(-1) in c-C3H₄⁺) to the CH2 torsional mode (ν₈⁺, A2 symmetry) and of the second-lowest-frequency mode (≈210 cm(-1) in c-C3H₄⁺) to a mode combining a CH out-of-plane with a CH2 rocking motion (ν₁₅⁺, B2 symmetry). The potential energy along the CH2 torsional coordinate is flat near the equilibrium structure and leads to a pronounced anharmonicity. AU - Vasilatou, K. AU - Michaud, J. M. AU - Baykusheva, Denitsa Rangelova AU - Grassi, G. AU - Merkt, F. ID - 14019 IS - 6 JF - The Journal of Chemical Physics KW - Physical and Theoretical Chemistry KW - General Physics and Astronomy SN - 0021-9606 TI - The cyclopropene radical cation: Rovibrational level structure at low energies from high-resolution photoelectron spectra VL - 141 ER - TY - JOUR AB - We present the detailed analysis of a new two-pulse orientation scheme that achieves macroscopic field-free orientation at the high particle densities required for attosecond and high-harmonic spectroscopies (Kraus et al 2013 arXiv:1311.3923). Carbon monoxide molecules are oriented by combining one-colour and delayed two-colour non-resonant femtosecond laser pulses. High-harmonic generation is used to probe the oriented wave-packet dynamics and reveals that a very high degree of orientation (Nup/Ntotal = 0.73–0.82) is achieved. We further extend this approach to orienting carbonyl sulphide molecules. We show that the present two-pulse scheme selectively enhances orientation created by the hyperpolarizability interaction whereas the ionization-depletion mechanism plays no role. We further control and optimize orientation through the delay between the one- and two-colour pump pulses. Finally, we demonstrate a complementary encoding of electronic-structure features, such as shape resonances, in the even- and odd-harmonic spectrum. The achieved progress makes two-pulse field-free orientation an attractive tool for a broad class of time-resolved measurements. AU - Kraus, P M AU - Baykusheva, Denitsa Rangelova AU - Wörner, H J ID - 14021 IS - 12 JF - Journal of Physics B: Atomic, Molecular and Optical Physics KW - Condensed Matter Physics KW - Atomic and Molecular Physics KW - and Optics SN - 0953-4075 TI - Two-pulse orientation dynamics and high-harmonic spectroscopy of strongly-oriented molecules VL - 47 ER - TY - JOUR AB - We report the observation of macroscopic field-free orientation, i.e., more than 73% of CO molecules pointing in the same direction. This is achieved through an all-optical scheme operating at high particle densities (>10(17)  cm(-3)) that combines one-color (ω) and two-color (ω+2ω) nonresonant femtosecond laser pulses. We show that the achieved orientation solely relies on the hyperpolarizability interaction as opposed to an ionization-depletion mechanism, thus, opening a wide range of applications. The achieved strong orientation enables us to reveal the molecular-frame anisotropies of the photorecombination amplitudes and phases caused by a shape resonance. The resonance appears as a local maximum in the even-harmonic emission around 28 eV. In contrast, the odd-harmonic emission is suppressed in this spectral region through the combined effects of an asymmetric photorecombination phase and a subcycle Stark effect, generic for polar molecules, that we experimentally identify. AU - Kraus, P. M. AU - Baykusheva, Denitsa Rangelova AU - Wörner, H. J. ID - 14020 IS - 2 JF - Physical Review Letters KW - General Physics and Astronomy SN - 0031-9007 TI - Two-pulse field-free orientation reveals anisotropy of molecular shape resonance VL - 113 ER -