Mass resolved MPI spectra of methyl iodide in the 430–490 nm region

Zhang, Bailin; Wang, Xiuyan; Lou, Nan-Quan; Zhang, Fangfang; Wei, Jie

doi:10.1016/s1386-1425(01)00388-2

Cited by 8 publications

(12 citation statements)

References 28 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…As less excess photon energy is available with increasing wavelength, fewer fragments are possible. This explanation agrees with the argument made in 2001 by Zhang, et al [42] who saw similar spectra from the various fragments using higher energy photons. The other possibility popular in the literature is that MPI occurs on the dissociated fragments.…”

Section: Methodssupporting

confidence: 93%

“…3. Later, Zhang et al compared the mass-resolved MPI signal from methyl iodide, but over the higher energy region 430-490 nm (2.53-2.88 eV) [42]. These authors also observed little difference between the spectra of the different fragments and argued that the fragments must have originated from the photodissociation of multiphoton-ionized molecular parent ions.…”

Section: Methodsmentioning

confidence: 99%

“…However, Lehr et al [34] in 2001 confirmed the simultaneous presence of neutral and cationic fragment channels. Also in 2001, Zhang et al [42] recorded MPI spectra of multiple mass fragments with photon energies from 2.9 down to 2.5 eV and concluded that because of the similar vibrational structure, each fragment originated from photodissociation of multiphoton ionized molecular parent ions. …”

Section: Imentioning

confidence: 99%

See 2 more Smart Citations

The Multiphoton Ionization Spectrum of Methyl Iodide Revisited: 1.67-2.2 ev Excitation

Scardino¹,

McDowell²,

Graham³

et al. 2011

JAMS

View full text Add to dashboard Cite

Abstract. The study of the multiphoton ionization of methyl iodide has a long and storied history. Here, we revisit this topic and present spectra of each of the photoionization and photodissociation fragments (C + , CH + , CH + 2 , CH + 3 , CH 3 I + , and I + ) using a custom time-offlight mass spectrometer and a tunable dye laser over the excitation range of 550-740 nm (2.2-1.67 eV). The choice of this wavelength range allows for excitation through the A state and resonant ionization through higher energy levels using 4+1, 5+1, or 6+1 photons for excitation and ionization. Although the various fragments yield very similar spectra, fewer fragment ions are observed with increasing wavelength.

show abstract

Section: Methodssupporting

confidence: 93%

Section: Methodsmentioning

confidence: 99%

Section: Imentioning

confidence: 99%

See 1 more Smart Citation

The Multiphoton Ionization Spectrum of Methyl Iodide Revisited: 1.67-2.2 ev Excitation

Scardino¹,

McDowell²,

Graham³

et al. 2011

JAMS

View full text Add to dashboard Cite

show abstract

“…Prior to ionization, CH 3 I has a total energy of 11.65 eV (∼5 h ν ), which is sufficient to produce [CH 3 I] + (X) ions in the 2 E 3/2 state (IP = 9.538 eV) as well as the higher lying 2 E 1/2 state (IP = 10.164 eV). MPI and photoelectron spectroscopic studies have shown that there is no preference for either state, and these two states are produced in nearly equal abundance 11, 22, 23…”

Section: Resultsmentioning

confidence: 99%

“…However, along with [CH 3 ] + , [I] + ions are observed down to the lowest intensity (∼3 × 10 9 W/cm 2 ) used in the present work. It has been observed that [CH 3 I] + ions produced in the higher vibrational levels of the Ã state, either by direct autoionization or following conversion from the B state, dissociate into CH 3 + I + 22. However, internal conversion (IC) from the ionic Ã state to the X state, followed by dissociation on the ground state surface giving rise to CH

_{3}^{+}

+ I, is also competing simultaneously as shown below: …”

Section: Resultsmentioning

confidence: 99%

Photoionization of CH₃I mediated by the C state in the visible and ultraviolet regions

Sharma

Vatsa

Rajasekhar

et al. 2005

Rapid Comm Mass Spectrometry

View full text Add to dashboard Cite

Three/two-photon resonant multiphoton ionization (MPI) of the CH3I monomer has been studied in the gas phase at 532 and 355 nm using time-of-flight mass spectrometry. Under low laser intensity (approximately 10(9) W/cm2) the mass spectra showed peaks at m/z 15, 127 and 142, corresponding to [CH3]+, [I]+ and [CH3I]+ species, at both these wavelengths. The laser power dependence for [CH3I]+, [I]+ and [CH3]+ ions showed a three-photon dependence at 532 nm. For the same three ions, photoionization studies at 355 nm gave a power dependence of 2. Both these results suggest that a vibronic energy level at approximately 7 eV, lying in the Rydberg C state, acts as a resonant intermediate level in ionization of CH3I. In the case of 355 nm, with increasing intensity additional peaks at m/z 139 and 141 were observed which could be assigned to [CI]+ and [CH2I]+ fragments. In contrast, for high intensity radiation at 532 nm ( approximately 2 x 10(10) W/cm2), only the [CI]+ fragment was observed. At these wavelengths, fragment ions observed in mass spectra mainly arise from photodissociation of the parent ion. Experiments at another wavelength in the visible region (564.2 nm) confirmed the results obtained at 532 nm. In order to assess the role of the A state in these MPI experiments, additional experiments were performed at 266 and 282.1 nm, which access the A state directly via a one-photon transition, and showed absence of a surviving precursor ion. Reaction energies for various possible dissociation channels of CH3I/[CH3I]+/[CH2I]+ were calculated theoretically at the MP2 level using the GAMESS electronic structure program.

show abstract

Tracing photoionisation behaviour of methyl iodide in gas phase: From isolated molecule to molecular aggregate

Das

Sharma

Vatsa

2017

Journal of Photochemistry and Photobiology C: Photochemistry Re

View full text Add to dashboard Cite

Mass resolved MPI spectra of methyl iodide in the 430–490 nm region

Cited by 8 publications

References 28 publications

The Multiphoton Ionization Spectrum of Methyl Iodide Revisited: 1.67-2.2 ev Excitation

The Multiphoton Ionization Spectrum of Methyl Iodide Revisited: 1.67-2.2 ev Excitation

Photoionization of CH₃I mediated by the C state in the visible and ultraviolet regions

Tracing photoionisation behaviour of methyl iodide in gas phase: From isolated molecule to molecular aggregate

Contact Info

Product

Resources

About

Mass resolved MPI spectra of methyl iodide in the 430–490 nm region

Cited by 8 publications

References 28 publications

The Multiphoton Ionization Spectrum of Methyl Iodide Revisited: 1.67-2.2 ev Excitation

The Multiphoton Ionization Spectrum of Methyl Iodide Revisited: 1.67-2.2 ev Excitation

Photoionization of CH3I mediated by the C state in the visible and ultraviolet regions

Tracing photoionisation behaviour of methyl iodide in gas phase: From isolated molecule to molecular aggregate

Contact Info

Product

Resources

About

Photoionization of CH₃I mediated by the C state in the visible and ultraviolet regions