Predissociation Dynamics of B State of Methyl Iodide with Femtosecond Pump-probe Technique

Wei, Zhengrong; Zhang, Feng; Wang, Yan-Rnei; Zhang, Bing

doi:10.1088/1674-0068/20/04/419-424

Cited by 14 publications

(45 citation statements)

References 33 publications

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“…Figure 4 shows the total translational energy distributions extracted from the images for nonresonant ionization of I and CH 3 (4a and 4b, respectively), and for resonant ionization of CH 3 v 2 = 0, 1, and 2 (4e, 4d, and 4c, respectively), at a pump-probe delay of 8 ps. Both our previous work 6 and the work of others 7 indicate that the dominant dissociation channel for the B 6s [2] state is to CH 3 + I*. The images for state-selective ionization of CH 3 allow us to assign the dominant peak in the corresponding translational energy distributions and thus internally calibrate Figures 4 c-e in a straightforward fashion.…”

Section: Energy Distribution Of Photofragments At 8 Psmentioning

confidence: 70%

“…14 This situation ensures that only the v=0 level of B-6s [2] state is excited by one photon of the pump. The probe wavelengths are chosen to photoionize selectively the methyl fragments as a function of their internal energy, while the atomic I fragments are ionized nonresonantly by using 403 nm photons.…”

Section: Resultsmentioning

confidence: 99%

“…The slower rise producing the plateau at longer times can be assigned to the photoionization of neutral fragments produced by the predissociation of the B-6s [2] state. This assignment is discussed in more detail below, and confirmed by using the velocity distributions determined in the imaging experiments.…”

Section: Choice Of the Probe Wavelengthmentioning

confidence: 99%

“…With an energy of excitation at 6.16 eV, 21 the maximum available energy is 3.80 eV for the I channel, and 2.86 eV for the I* channel. The transition from the ground state to the B-6s [2] state has a perpendicular charactere. Thus, for predissociation that is slightly faster than the rotational period of the parent, the fragments issued from a non-vibrating parent are expected to be preferentially ejected perpendicular to the polarization axis of the pump beam, as it can be seen for the image recorded for I fragments shown in Figure 3a.…”

Section: Energy Distribution Of Photofragments At 8 Psmentioning

confidence: 99%

“…Here we examine the predissociation of vibrationless level of the B-6s [2] state by using timeresolved photoion velocity map imaging. The CH 3 and I fragments were selectively ionized by REMPI schemes that allow the determination of the vibrational distribution of the CH 3 fragment.…”

Section: Introductionmentioning

confidence: 99%

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Time-resolved predissociation of the vibrationless level of the B state of CH3I

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Staedter

et al. 2011

Phys. Chem. Chem. Phys.

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The predissociation dynamics of the vibrationless level of the first Rydberg state 6s (B 2 E) state of CH 3 I has been studied by femtosecond-resolved velocity map imaging of both the CH 3 and I photofragments. The kinetic energy distributions of the two fragments have been recorded as a function of the pump-probe delay, and as a function of excitation within the umbrella and stretching vibrational modes of the CH 3 fragment. These observations are made by using (2+1) Resonant Enhanced MultiPhoton Ionization (REMPI) via the 3p z 2 A 2 " state of CH 3 to detect specific vibrational levels of CH 3 . The vibrational branching fractions of the CH 3 are recovered by using the individual vibrationally state-selected CH 3 distributions to fit the kinetic energy distribution obtained by using nonresonant multiphoton ionization of either the I or CH 3 fragment. The angular distributions and rise times of the two fragments differ significantly. These observations can be rationalized through a consideration of the alignment of the CH 3 fragment and the effect of this alignment on its detection efficiency.Two extra dissociation channels are detected: one associated with Rydberg states near 9.2 eV that were observed previously in photoelectron studies, and one associated with photodissociation of the parent cation around 15 eV.

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Section: Energy Distribution Of Photofragments At 8 Psmentioning

confidence: 70%

Section: Resultsmentioning

confidence: 99%

Section: Choice Of the Probe Wavelengthmentioning

confidence: 99%

Section: Energy Distribution Of Photofragments At 8 Psmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Time-resolved predissociation of the vibrationless level of the B state of CH3I

Thiré

Cireasa

Staedter

et al. 2011

Phys. Chem. Chem. Phys.

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Ultrafast Dynamics of o‐Bromofluorobenzene Studied by Time‐Resolved Photoelectron Imaging

et al. 2009

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Photodissociation dynamics and rotational wave packet coherences of o-bromofluorobenzene are studied by femtosecond time-resolved photoelectron imaging [figure: see text]. The decay of different photoelectron rings shows the population decay of states from which the lifetimes of different states are determined. The variation of photoelectron angular distributions reflects the evolution of rotational coherences.Photodissociation dynamics and rotational wave packet coherences of o-bromofluorobenzene are studied by femtosecond time-resolved photoelectron imaging (TR-PEI) spectroscopy combined with the (1+2') resonance-enhanced multiphoton ionization (REMPI). Photoelectron kinetic energy and angular distributions indicate ionization dynamics from some Rydberg states at the (1+1') photon energy. The lifetimes of the S(1) (A') and T(2) (A') states are determined from the decay of the photoelectron signals to be 38 ps and 27 ps. The electron population decay of the two states is attributed to predissociation and tunneling dissociation. The variation of time-dependent anisotropy parameters in the first 5 ps shows the rotational wave coherences of molecule.

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Photodissociation/photoionization processes of chlorobromomethane induced by femtosecond laser pulses with pump-probe scheme

et al. 2008

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The photodissociation/photoionization processes of chlorobromomethane (CH 2 BrCl) induced by femtosecond laser pulses have been investigated using pump-probe scheme combined with the time-of-flight mass spectra. The dominate photoproducts are observed at different delay time of the pump (400 nm) and probe (800 nm) pulses and the corresponding time-dependence of them is obtained. The results show that the decaying time of the molecule CH 2 BrCl in the A-band is in the 100 fs. The decaying tendencies of the fragment ions (CH 2 Cl + and CH 2 Br + ) and the parent ion (CH 2 BrCl + ) are almost the same and the relative ratios of the yields of them keep constant during the delay time of 0 to 150 fs. These facts suggest that the fragment ions come from the fragmentation of the parent ions in excited electronic states. The probabilities to form CH 2 Cl + and CH 2 Br + are obtained from the relative ratio of the ion intensity and are about 71.6% and 14.2%, respectively. chlorobromomethane, femtosecond, pump-probe, photodissociation, photoionizationUnderstanding of the photochemistry of halomethanes has received significant attention in recent decades due to two main reasons. On one hand, the halogen atoms and halogen-containing radicals have been realized as chemical species for the destruction of stratospheric ozone [1][2][3] ; on the other hand, the halomethanes have been chosen as prototypes for mode specific photochemistry upon laser excitation [4,5] .The chlorobromomethane, as a typical monohalomethane, has been extensively studied from experimental [5][6][7][8] and theoretical [9][10][11] point of view as an ideal research object in the photochemistry field. Now, the general features of its photodissociation dynamics in ultraviolet region have been well understood. Compared with CH 3 I molecule [4] , photodissociation of CH 2 BrCl molecule in ultraviolet region involves more states because of the lowering of the molecular symmetry from C 3v to C s , which results in the splitting of the degenerate states, 3 Q 1 and 1 Q 1 , into [2A′, 1A″] and [4A′, 2A″], respectively. The 3 Q 0 state in C 3v symmetry becomes the 3A' states in C s symmetry. The 3A′ state diabatically correlates to the CH 2 Cl+Br*( 2 P 1/2 ) products, but an avoid crossing occurs between the 3A′ and 4A′ states, resulting in an adiabatic correlation of the 3A′ to the CH 2 Cl+Br( 2 P 3/2 ) products and the 4A′ state to the CH 2 Cl+Br*( 2 P 1/2 ) products. The other states 2A′, 1A″ and 2A″ correlate adiabatically the ground state products CH 2 Cl+Br( 2 P 3/2 ). In the 193-267nm region, however, no breaking of C-Cl bonds happen when CH 2 BrCl molecules absorb a single ultraviolet photon [8] .With the advent of the advanced femtosecond laser technology [12] , now the combination of ultrashort laser

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Predissociation Dynamics of B State of Methyl Iodide with Femtosecond Pump-probe Technique

Cited by 14 publications

References 33 publications

Time-resolved predissociation of the vibrationless level of the B state of CH3I

Time-resolved predissociation of the vibrationless level of the B state of CH3I

Ultrafast Dynamics of o‐Bromofluorobenzene Studied by Time‐Resolved Photoelectron Imaging

Photodissociation/photoionization processes of chlorobromomethane induced by femtosecond laser pulses with pump-probe scheme

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