Imaging of Ultrafast Molecular Elimination Reactions

Roeterdink, Wim G.; Rijs, Anouk M.; Janssen, Maurice H. M.

doi:10.1021/ja055658x

Cited by 16 publications

(16 citation statements)

References 23 publications

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“…More recently, velocity map imaging 17,18 used in combination with pump-probe femtosecond laser pulses has demonstrated to be a powerful technique to study the real time dynamics of complex systems. 3,8,[19][20][21] Femtosecond imaging experiments include photoelectron 3,22 and photoionphotoelectron coincidence detection. 3,6,7,22 Here we have studied the femtosecond photodissociation dynamics of CH 3 I from the A band both experimentally and theoretically.…”

Section: Introductionmentioning

confidence: 99%

A detailed experimental and theoretical study of the femtosecond A-band photodissociation of CH3I

Nalda

Durá

Garcı́a-Vela

et al. 2008

The Journal of Chemical Physics

101

184

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The real time photodissociation dynamics of CH 3 I from the A band has been studied experimentally and theoretically. Femtosecond pump-probe experiments in combination with velocity map imaging have been carried out to measure the reaction times ͑clocking͒ of the different ͑nonadiabatic͒ channels of this photodissociation reaction yielding ground and spin-orbit excited states of the I fragment and vibrationless and vibrationally excited ͑symmetric stretch and umbrella modes͒ CH 3 fragments. The measured reaction times have been rationalized by means of a wave packet calculation on the available ab initio potential energy surfaces for the system using a reduced dimensionality model. A 40 fs delay time has been found experimentally between the channels yielding vibrationless CH 3 ͑ =0͒ and I͑ 2 P 3/2 ͒ and I * ͑ 2 P 1/2 ͒ that is well reproduced by the calculations. However, the observed reduction in delay time between the I and I * channels when the CH 3 fragment appears with one or two quanta of vibrational excitation in the umbrella mode is not well accounted for by the theoretical model.

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Section: Introductionmentioning

confidence: 99%

A detailed experimental and theoretical study of the femtosecond A-band photodissociation of CH3I

Nalda

Durá

Garcı́a-Vela

et al. 2008

The Journal of Chemical Physics

101

184

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“…In 2000 we followed the German design notes of Gerlich in the construction of our first piezovalve that we operated at 1 kHz repetition rate in femtosecond ion imaging experiments. [14][15][16][17] Recent demands in our group 18,19 to run experiments at 5 kHz and the need to make translationally ͑and rotationally͒ cold pulsed molecular beams inspired us to reconsider the design of the cantilever piezovalve.…”

Section: Introductionmentioning

confidence: 99%

A short pulse (7 μs FWHM) and high repetition rate (dc-5kHz) cantilever piezovalve for pulsed atomic and molecular beams

Irimia

Dobrikov

Kortekaas

et al. 2009

Review of Scientific Instruments

Self Cite

110

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In this paper we report on the design and operation of a novel piezovalve for the production of short pulsed atomic or molecular beams. The high speed valve operates on the principle of a cantilever piezo. The only moving part, besides the cantilever piezo itself, is a very small O-ring that forms the vacuum seal. The valve can operate continuous ͑dc͒ and in pulsed mode with the same drive electronics. Pulsed operation has been tested at repetition frequencies up to 5 kHz. The static deflection of the cantilever, as mounted in the valve body, was measured as a function of driving field strength with a confocal microscope. The deflection and high speed dynamical response of the cantilever can be easily changed and optimized for a particular nozzle diameter or repetition rate by a simple adjustment of the free cantilever length. Pulsed molecular beams with a full width at half maximum pulse width as low as 7 s have been measured at a position 10 cm downstream of the nozzle exit. This represents a gas pulse with a length of only 10 mm making it well matched to for instance experiments using laser beams. Such a short pulse with 6 bar backing pressure behind a 150 m nozzle releases about 10 16 particles/pulse and the beam brightness was estimated to be 4 ϫ 10 22 particles/ ͑s str͒. The short pulses of the cantilever piezovalve result in a much reduced gas load in the vacuum system. We demonstrate operation of the pulsed valve with skimmer in a single vacuum chamber pumped by a 520 l/s turbomolecular pump maintaining a pressure of 5 ϫ 10 −6 Torr, which is an excellent vacuum to have the strong and cold skimmed molecular beam interact with laser beams only 10 cm downstream of the nozzle to do velocity map slice imaging with a microchannel-plate imaging detector in a single chamber. The piezovalve produces cold and narrow ͑⌬v / v =2% -3%͒ velocity distributions of molecules seeded in helium or neon at modest backing pressures of only 6 bar. The low gas load of the cantilever valve makes it possible to design very compact single chamber molecular beam machines with high quality cold and intense supersonic beams. The high speed cantilever piezovalve may find broad applicability in experiments where short and strong gas pulses are needed with only modest pumping, the effective use of ͑expensive͒ samples, or the production of cold atomic and molecular beams.

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“…50 ee 315 Ultrafast molecular elimination of iodine from IF 2 C-CF 2 I has been studied using the velocity map ion imaging technique in combination with femtosecond pump-probe laser excitation. 51 By varying the femtosecond delay between pump and probe pulse, it has been found that elimination of molecular iodine is a concerted process, although the two carbon-iodine bonds are not broken synchronously.…”

Section: Other Reactionsmentioning

confidence: 99%

Elimination Reactions

Birsa

2010

Organic Reaction Mechanisms · 2006

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Imaging of Ultrafast Molecular Elimination Reactions

Cited by 16 publications

References 23 publications

A detailed experimental and theoretical study of the femtosecond A-band photodissociation of CH3I

A detailed experimental and theoretical study of the femtosecond A-band photodissociation of CH3I

A short pulse (7 μs FWHM) and high repetition rate (dc-5kHz) cantilever piezovalve for pulsed atomic and molecular beams

Elimination Reactions

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