Competitive photodecomposition reactions of chloroiodomethane

Schmitt, G.; Comes, F. J.

doi:10.1016/1010-6030(87)80002-3

Cited by 20 publications

(12 citation statements)

References 24 publications

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“…30 At different wavelengths, preferential dissociation of either halogen atom can be observed, 30 as well as the elimination of ICl. [29][30][31][32]37 Similar multi-pathway chemistry is also exhibited by CH 2 BrI. 38,39 The excitation wavelength used in this study (272 nm) lies near the centre of the A-band of CH 2 ClI (225-325 nm).…”

Section: Introductionmentioning

confidence: 61%

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Coulomb explosion imaging of CH3I and CH2ClI photodissociation dynamics

Allum

Burt

Amini

et al. 2018

The Journal of Chemical Physics

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The photodissociation dynamics of CH 3 I and CH 2 ClI at 272 nm were investigated by time-resolved Coulomb explosion imaging, with an intense non-resonant 815 nm probe pulse. Fragment ion momenta over a wide m/z range were recorded simultaneously by coupling a velocity map imaging spectrometer with a pixel imaging mass spectrometry camera. For both molecules, delay-dependent pump-probe features were assigned to ultraviolet-induced carbon-iodine bond cleavage followed by Coulomb explosion. Multi-mass imaging also allowed the sequential cleavage of both carbon-halogen bonds in CH 2 ClI to be investigated. Furthermore, delay-dependent relative fragment momenta of a pair of ions were directly determined using recoil-frame covariance analysis. These results are complementary to conventional velocity map imaging experiments and demonstrate the application of time-resolved Coulomb explosion imaging to photoinduced real-time molecular motion.

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Section: Introductionmentioning

confidence: 61%

“…The analogous photodissociation of CH 2 ClI has been the subject of fewer studies. [28][29][30][31][32] Absorption by CH 3 I in its A-band (220-350 nm) arises due to excitations to three repulsive electronic states, as depicted in Fig. 1.…”

Section: Introductionmentioning

confidence: 99%

Coulomb explosion imaging of CH3I and CH2ClI photodissociation dynamics

Allum

Burt

Amini

et al. 2018

The Journal of Chemical Physics

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“…Chloroiodomethane's A-band absorption band has its peak ϳ270 nm and an extinction coefficient of about 540 mol Ϫ1 L cm Ϫ1 in cyclohexane solution. 62 The absorption spectrum of chloroiodomethane is red shifted and more intense than the corresponding A-band absorption of iodomethane which is ϳ258 nm and has an extinction coefficient of about 430 mol Ϫ1 L cm Ϫ1 in cyclohexane solution. The interaction between the C-Cl and C-I chromophores may be responsible for the red shifting and enhancement of the A-band absorption in chloroiodomethane.…”

Section: Introductionmentioning

confidence: 98%

“…The interaction between the C-Cl and C-I chromophores may be responsible for the red shifting and enhancement of the A-band absorption in chloroiodomethane. Laser flash photolysis experiments performed by Schmitt and Comes 62 on chloroiodomethane have determined that the predominant primary process after photoexcitation in the A-band absorption leads to cleavage of the C-I bond similar to iodomethane and other iodoalkanes.…”

Section: Introductionmentioning

confidence: 99%

Early-time photodissociation dynamics of chloroiodomethane in the A-band absorption from resonance Raman intensity analysis

Kwok

Phillips

1996

The Journal of Chemical Physics

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We have obtained resonance Raman spectra and absolute Raman cross sections for h 2-chloroiodomethane ͑fourteen excitation wavelengths between 200 nm and 355 nm͒ and d 2-chloroiodomethane ͑for 282.4 nm excitation͒ in cyclohexane solution. Most of the intensity in the A-band resonance Raman spectra appears in the nominal C-I stretch overtones progression and combination bands of the nominal C-I stretch overtones with the fundamentals of the CH 2 wag, CH 2 scissor, and the Cl-C-I bend or C-Cl stretch fundamentals. The A-band absorption and absolute resonance Raman intensities were simulated using a simple model which included preresonant contributions to the fundamental Raman peaks and time-dependent wave packet calculations. The motion of the wave packet on the excited state surface was converted from dimensionless normal coordinates into internal coordinates using the results of normal coordinate calculations. The A-band short-time photodissociation dynamics of chloroiodomethane shows that the C-I bond lengthens, the I-C-Cl and H-C-I angles become smaller, and the H-C-Cl angles become larger. These internal coordinate motions which are associated with relatively low frequency modes are consistent with a simple impulsive ''soft'' radical model of the photodissociation and the CH 2 Cl group changing to a more planar structure. However, the C-H bond length does not change much and the H-C-H angle ͑associated with higher frequency modes͒ becomes slightly smaller which is inconsistent with the ''soft'' radical model and the CH 2 Cl group changing to a more planar structure. This suggests that an impulsive ''semirigid'' radical model may be more appropriate than the ''soft'' radical model to qualitatively describe the chloroiodomethane photodissociation. An ambiguity in the assignment of the 724 cm Ϫ1 Raman peak and its associated combination bands to combination bands of the nominal C-I stretch overtones with the fundamentals of the Cl-C-I bend or C-Cl stretch fundamentals limits what we are able to determine about the C-Cl bond length changes during the initial stages of the photodissociation.

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“…Dihalomethanes offer a rich source of photochemistry in the gas-and solution-phases [27][28][29][30][31][32][33][34][35][36]. Their geminal halogens allow a complex system of repulsive excited states to be accessed in the UV, making them archetypes for mode-selective chemistry.…”

Section: Introductionmentioning

confidence: 99%

Coulomb-explosion imaging of concurrent CH2BrI photodissociation dynamics

Burt¹,

Boll²,

Lee³

et al. 2017

Phys. Rev. A

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The dynamics following laser-induced molecular photodissociation of gas-phase CH 2 BrI at 271.6 nm were investigated by time-resolved Coulomb explosion imaging using intense near-IR femtosecond laser pulses. The observed delay-dependent photofragment momenta reveal that CH 2 BrI undergoes C-I cleavage, depositing 65.6% of the available energy into internal product states, and that absorption of a second UV photon breaks the C-Br bond of CH 2 Br. Simulations confirm that this mechanism is consistent with previous data recorded at 248 nm, demonstrating the sensitivity of Coulomb explosion imaging as a real-time probe of chemical dynamics.2

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Competitive photodecomposition reactions of chloroiodomethane

Cited by 20 publications

References 24 publications

Coulomb explosion imaging of CH3I and CH2ClI photodissociation dynamics

Coulomb explosion imaging of CH3I and CH2ClI photodissociation dynamics

Early-time photodissociation dynamics of chloroiodomethane in the A-band absorption from resonance Raman intensity analysis

Coulomb-explosion imaging of concurrent CH2BrI photodissociation dynamics

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