Photodissociation spectroscopy of stored CH+ and CD+ ions: Analysis of the<i>b</i> 3Σ−-<i>a</i> 3Π system

Hechtfischer, Ulrich; Rostas, J.; Lange, Michael; Linkemann, J.; Schwalm, D.; Wester, Roland; Wolf, A.; Zajfman, D.

doi:10.1063/1.2800004

Cited by 17 publications

(11 citation statements)

References 36 publications

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“…The photodissociation spectrum is then recorded by simply monitoring the induced ion trap loss as a function of excitation energy. This technique, which we estimate should be easily applicable whenever the photofragments' massto-charge ratio differs by ≥15% from the parent molecular ion, may be a simple alternative to both photofragment mass spectrometry [13] and storage ring based pho-todissociation spectroscopy [14].…”

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confidence: 99%

Molecular-ion trap-depletion spectroscopy of BaCl+

et al. 2011

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We demonstrate a simple technique for molecular ion spectroscopy. BaCl + molecular ions are trapped in a linear Paul trap in the presence of a room-temperature He buffer gas and photodissociated by driving an electronic transition from the ground X 1 Σ + state to the repulsive wall of the A 1 Π state. The photodissociation spectrum is recorded by monitoring the induced trap loss of BaCl + ions as a function of excitation wavelength. Accurate molecular potentials and spectroscopic constants are determined. Comparison of the theoretical photodissociation cross-sections with the measurement shows excellent agreement. This study represents the first spectroscopic data for BaCl + and an important step towards the production of ultracold ground-state molecular ions. [5]. In pursuit of these goals, several groups have recently initiated work [6-9] to realize samples of cold, absolute ground-state molecular ions. In fact, Refs. [7][8][9] have already reported the demonstration of species-specific cooling methods to produce molecular ions in the lowest few rotational states.While these molecular ion cooling efforts, which include ultracold atom sympathetic cooling [6], rovibrational optical pumping [7,8], and state-selective ionization [9], are diverse in approach, they share the common need for detailed spectroscopic understanding of diatomic ions. However, compared to that of neutral molecules, spectroscopic data for molecular ions is scarce. This can be attributed to the typically short lifetimes of molecular ions due to fast ion-molecule reactions [10]. A systematic review of the available spectroscopic data for simple diatomic ions was carried out by Berkowitz and Groeneveld [11] in 1983. In recent years, interest has shifted towards large molecular ions, atomic and molecular clusters, and multiply charged ions [12]. Thus, for ultracold molecular ion research to realize its full potential, a new effort in small molecular ion spectroscopy is required.Here, we report the use of a simple and general technique to record the first spectroscopic data for BaCl + -the molecular ion we have proposed to cool in Ref. As an ionically-bonded molecule composed of two closedshell atomic ions, Ba 2+ and Cl − , BaCl + exhibits reduced chemical reactivity compared to other ions and is energetically forbidden from undergoing 2-body chemical reactions with the ultracold calcium atoms used for sympathetic cooling [6]. Further, its large dipole moment and convenient rotational splitting are promising for cavity QED experiments [4]. Thus, these results are important not only as the demonstration of a technique for recording molecular ion spectroscopy, but also as an important first step towards the use and application of a generic, robust method for the production of cold ground-state molecular ions.Spectroscopic data is taken using a trap-depletion approach. BaCl + ions are trapped in a linear Paul trap in the presence of a room-temperature He buffer gas and photodissociated by driving an electronic transition from the ground X 1 Σ + st...

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confidence: 99%

Molecular-ion trap-depletion spectroscopy of BaCl+

et al. 2011

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“…6, are very small due to limited Franck-Condon overlap. Levels of the b 3 Σ − state are predissociated by the c 3 Σ + state for v > ∼ 4, see Hechtfischer et al (2007) for a detailed analysis, and the probability of forming levels with v < ∼ 4, which would decay to the a 3 Π state (Biglari et al 2014), is small. We ignored predissociation and radiative cascading and estimated the cross sections using the quantum-mechanical approach, Eq.…”

Section: Triplet States Of C( 3 P) and H +mentioning

confidence: 99%

Radiative association of C(3P) and H+: triplet states

Babb

McLaughlin

2017

Monthly Notices of the Royal Astronomical Society

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The radiative association of C( 3 P) and H + is investigated by calculating cross sections for photon emission into bound ro-vibrational states of CH + from the vibrational continua of initial triplet d 3 Π or b 3 Σ − states. Potential energy curves and transition dipole moments are calculated using multi-reference configuration interaction (MRCI) methods with AV6Z basis sets. The cross sections are evaluated using quantum-mechanical methods and rate coefficients are calculated. The rate coefficients are about 100 times larger than those for radiative association of C + ( 2 P o ) and H from the A 1 Π state. We also confirm that the formation of CH + by radiative association of C + ( 2 P o ) and H via the triplet c 3 Σ + state is a minor process.

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“…The CD + ions arrive at the interaction region with the laser in a combination of the electronic ground state, X 1 + , and the lowest triplet state, namely, the a 3 , which has a lifetime of a few seconds [54]-much longer than the few tens of microseconds flight time through our apparatus. This long-lived triplet state may constitute about half the CD + beam [54,55]. Moreover, the vibrational distribution in both electronic states is possibly vibrationally "hot" [56] and may affect the outcome of the laser interaction with the CD + molecular ions.…”

Section: Experimental Methodsmentioning

confidence: 99%

“…The C + D + final products can also be reached by dissociation of the long-lived a 3 state present in the CD + beam [54,55]. The main path leading to low-KER C + D + breakup, shown in Fig.…”

Section: Dissociation Pathways Leading Tomentioning

confidence: 99%

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Fragmentation ofCD+induced by intense ultrashort laser pulses

et al. 2015

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The fragmentation of CD + in intense ultrashort laser pulses was investigated using a coincidence threedimensional momentum imaging technique improved by employing both transverse and longitudinal electric fields. This allowed clear separation of all fragmentation channels and the determination of the kinetic energy release down to nearly zero, for a molecule with significant mass asymmetry. The most probable dissociation pathways for the two lowest dissociation limits, C + + D and C + D + , were identified for both 22-fs, 798-nm and 50-fs, 392-nm pulses. Curiously, the charge asymmetric dissociation of CD 2+ was not observed for 392-nm photons, even though it was clearly visible for the fundamental 798 nm at the same peak intensity.

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Photodissociation spectroscopy of stored CH+ and CD+ ions: Analysis of theb 3Σ−-a 3Π system

Cited by 17 publications

References 36 publications

Molecular-ion trap-depletion spectroscopy of BaCl+

Molecular-ion trap-depletion spectroscopy of BaCl+

Radiative association of C(3P) and H+: triplet states

Fragmentation ofCD+induced by intense ultrashort laser pulses

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