Generation of the simplest rotational wave packet in a diatomic molecule: Tracing a two-level superposition in the time domain

Przystawik, Andreas; Kickermann, A.; Al-Shemmary, A.; Düsterer, S.; Ellis, Andrew M.; Haeften, K. von; Harmand, M.; Ramakrishna, S.; Redlin, H.; Schroedter, L.; Schulz, Michael; Seideman, Tamar; Stojanović, Nikola; Szekely, Joshua E.; Tavella, F.; Toleikis, S.; Laarmann, Tim

doi:10.1103/physreva.85.052503

Cited by 10 publications

(6 citation statements)

References 30 publications

(33 reference statements)

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“…The resulting power spectra, displayed in Fig. 1(a2)-(c2) contain distinct peaks, just as for rotational wave packets in gas phase molecules [17][18][19][20]. There, the peaks reflect the frequencies of the nonzero matrix elements JM | cos 2 θ 2D |J M , i.e.…”

mentioning

confidence: 89%

Rotational coherence spectroscopy of molecules in helium nanodroplets: Reconciling the time and the frequency domains

Chatterley,

Christiansen,

Schouder

et al. 2020

Preprint

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Alignment of OCS, CS 2 and I 2 molecules embedded in helium nanodroplets is measured as a function of time following rotational excitation by a non-resonant, comparatively weak ps laser pulse. The distinct peaks in the power spectra, obtained by Fourier analysis, are used to determine the rotational, B, and centrifugal distortion, D, constants. For OCS, B and D match the values known from IR spectroscopy. For CS 2 and I 2 , they are the first experimental results reported. The alignment dynamics calculated from the gas-phase rotational Schrödinger equation, using the experimental in-droplet B and D values, agree in detail with the measurement for all three molecules. The rotational spectroscopy technique for molecules in helium droplets introduced here should apply to a range of molecules and complexes.

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confidence: 89%

Rotational coherence spectroscopy of molecules in helium nanodroplets: Reconciling the time and the frequency domains

Chatterley,

Christiansen,

Schouder

et al. 2020

Preprint

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“…A much clearer picture is obtained when a discrete Fourier transform is performed, producing a rotational frequency spectrum. 87 The discrete Fourier transform, F u , is dened by…”

Section: Time-resolved Alignment and Fourier Transformationmentioning

confidence: 99%

“…Revivals of small acetylene-helium clusters (C 2 H 2 -He n ) are difficult to directly identify in the alignment scan because of the dominant signals from free acetylene rotation. A much clearer picture is obtained when a discrete Fourier transform is performed, producing a rotational frequency spectrum 87 .…”

Section: Time-resolved Alignment and Fourier Transformationmentioning

confidence: 99%

Formation of coherent rotational wavepackets in small molecule-helium clusters using impulsive alignment

et al. 2014

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We show that rotational line spectra of molecular clusters with near zero permanent dipole moments can be observed using impulsive alignment. Aligned rotational wavepackets were generated by non-resonant interaction with intense femtosecond laser pump pulses and then probed using Coulomb explosion by a second, time-delayed femtosecond laser pulse. By means of a Fourier transform a rich spectrum of rotational eigenstates was derived. For the smallest cluster, C 2 H 2 -He, we were able to establish essentially all rotational eigenstates up to the dissociation threshold on the basis of theoretical level predictions. The C 2 H 2 -He complex is found to exhibit distinct features of large amplitude motion and very early onset of free internal rotor energy level structure.

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“…(C 2 H 2 -He n ) are difficult to directly identify in the alignment scan because of the dominant signals from free (unclustered) acetylene. A much clearer picture is obtained when a Fourier transform is performed, producing a rotational frequency spectrum [22].…”

Section: Fig 2 (Color Online)mentioning

confidence: 99%

Probing the Structure and Dynamics of Molecular Clusters Using Rotational Wave Packets

et al. 2014

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Rotational wave packets of the weakly bound C 2 H 2 -He complex have been created using impulsive alignment. The coherent rotational dynamics were monitored for 600 ps enabling extraction of a frequency spectrum showing multiple rotational energy levels up to J ¼ 4. spectrum has been combined with ab initio calculations to show that the complex has a highly delocalized structure and is bound only by ca. 7 cm −1 . The experiments demonstrate how highly featured rotational spectra can be obtained from an extremely cold environment where only the lowest rotational energy states are initially populated. DOI: 10.1103/PhysRevLett.113.043004 PACS numbers: 33.20.-t, 33.80.-b, 36.40.Mr Weakly bound molecular complexes are important model systems for condensed matter held together by van der Waals forces [1]. The weak binding leads to large amplitude motion and delocalized structures that are often reflected in complex rotational spectra that cannot easily be categorized through rigid rotor models. Furthermore, obtaining these spectral features imposes practical problems associated with the very low temperatures that are required to form weakly bound complexes. The low temperatures imply the population of only the lowest quantum states. Consequently, the features in conventional rotational (microwave) spectroscopy comprise only a few lines-often not enough for a comprehensive analysis of the structure of the complex [2].A potential solution to this problem is to use impulsive alignment to generate rotational wave packets through the nonresonant interaction of an intense laser field with a molecule, aligning it in space [3]. Tuning the laser pulse duration and intensity controls the number of rotational eigenstates that contribute to the wave packets. Using this technique for isolated molecules it is possible to monitor the evolution of alignment in time, simultaneously obtaining information on the rotational dynamics and structure [3][4][5][6][7][8][9][10]. The extension of this technique to complex systems where weak interactions are important has been postulated theoretically [11], and demonstrated on the very simplest of systems, noble-gas dimers [12]. The extension of impulsive alignment to van der Waals complexes with internal and delocalized structures remains a challenge. This is due in part to the weak binding and floppy nature of the complex, but also due to the increased complexity of the resulting rotational spectrum, such that currently, to the best of our knowledge, no such measurement has been reported.This approach may also have potential for exploring liquids, where the wave-packet dynamics will be sensitive to dephasing. A particularly promising liquid to begin such studies is superfluid helium. Frequency-domain spectra of molecules embedded into large superfluid helium droplets show sharp rotational transitions, suggesting that wave packets will not dephase [2,13]. However, the recent attempt to impulsively align molecules in large helium droplets by Pentlehner et al. suggests that this may not be th...

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Generation of the simplest rotational wave packet in a diatomic molecule: Tracing a two-level superposition in the time domain

Cited by 10 publications

References 30 publications

Rotational coherence spectroscopy of molecules in helium nanodroplets: Reconciling the time and the frequency domains

Rotational coherence spectroscopy of molecules in helium nanodroplets: Reconciling the time and the frequency domains

Formation of coherent rotational wavepackets in small molecule-helium clusters using impulsive alignment

Probing the Structure and Dynamics of Molecular Clusters Using Rotational Wave Packets

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