Vacuum-ultraviolet mass-analyzed threshold ionization spectra of iodobutane isomers: Conformer-specific ionization and ion-core dissociation followed by ionization

Park, Sang Tae; Kim, Sang Kyu; Kim, Myoung Soo

doi:10.1063/1.1386786

Cited by 21 publications

(15 citation statements)

References 25 publications

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“…This value agrees well with the measured transient spectrum. The signal at negative time delays corresponds to an excitation to high-lying Rydberg states ( 51 ). The time-resolved map of the associated asymmetry β 2 parameters is shown in the Supplementary Materials (fig.…”

Section: Resultsmentioning

confidence: 99%

Femtosecond photoelectron circular dichroism of chemical reactions

et al. 2022

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Understanding the chirality of molecular reaction pathways is essential for a broad range of fundamental and applied sciences. However, the current ability to probe chirality on the time scale of primary processes underlying chemical reactions remains very limited. Here, we demonstrate time-resolved photoelectron circular dichroism (TRPECD) with ultrashort circularly polarized vacuum-ultraviolet (VUV) pulses from a tabletop source. We demonstrate the capabilities of VUV-TRPECD by resolving the chirality changes in time during the photodissociation of atomic iodine from two chiral molecules. We identify several general key features of TRPECD, which include the ability to probe dynamical chirality along the complete photochemical reaction path, the sensitivity to the local chirality of the evolving scattering potential, and the influence of electron scattering off dissociating photofragments. Our results are interpreted by comparison with high-level ab-initio calculations of transient PECDs from molecular photoionization calculations. Our experimental and theoretical techniques define a general approach to femtochirality.

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Section: Resultsmentioning

confidence: 99%

Femtosecond photoelectron circular dichroism of chemical reactions

et al. 2022

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“…In Table , the standard reaction enthalpies at 298 K (in kJ mol -1 ) have been calculated and are listed. The heats of formation are taken from the NIST compilation. , Note that the tert -butyl ion heat of formation has been recently revised, and a value of Δ H f ° 298 ( t -C 4 H 9 + ) = 711 kJ/mol from recent experimental − and theoretical studies is used, which is 20 kJ/mol higher than previous experimental measurements. Figure shows corrected (see below) primary ion decay plots for the reactions of CH 3 + , HCO + , C 2 H 5 + , s -C 3 H 7 + , and t -C 4 H 9 + with O 3 .…”

Section: Resultsmentioning

confidence: 99%

Oxidation of Alkyl Ions, C_nH₂_n₊₁⁺ (n = 1−5), in Reactions with O₂ and O₃ in the Gas Phase

Williams¹,

Knighton²,

Midey³

et al. 2004

J. Phys. Chem. A

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Rate constants and product ion branching fractions are reported for the reactions of CH 3 + , C 2 H 5 + , s-C 3 H 7 + , s-C 4 H 9 + , t-C 4 H 9 + , and t-C 5 H 11 + with O 2 and O 3 at 300 K in a variable-temperature selected-ion flow tube (VT-SIFT). The reaction rate constant for CH 3 + with O 3 is large and approximately equal to the thermal energy capture rate constant given by the Su-Chesnavich equation. The C 2 H 5 + , s-C 3 H 7 + , and s-C 4 H 9 + ions are somewhat less reactive, reacting at approximately 7-46% of the thermal capture rate. The HCO + and C 2 H 3 O + ions are the major products in these reactions. The t-C 4 H 9 + and t-C 5 H 11 + ions are found to be unreactive, with rate constants <5 × 10 -12 cm 3 s -1 , which is the present detection limit of our apparatus using this ozone source. Ozone is a singlet in its ground state, and ab initio calculations at the B3LYP/6-31G(d) level of theory indicate that reactant complexes can be formed, decreasing in stability with the size of alkyl chains attached to the cationic carbon atom. The decreasing reactivity of the alkyl ions with increasing order of the carbocation is attributed to a greatly reduced O 3 binding energy. The ions listed above do not undergo twobody reactions with O 2 , k < 5 × 10 -13 cm 3 s -1 , despite the availability of reaction channels with exothermicities of several hundred kilojoules per mole. Ab initio calculations at the B3LYP/6-31G(d) level of theory indicate that the O 2 reaction systems form weak complexes with large C-O bond distances (repulsive at smaller distances) on the lowest energy triplet potential energy surface. Access to the singlet surface is required for bond formation; however, this surface is not accessible at thermal energies.

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“…The PFI-PEPICO 10 and MATI 11,14 methods require highresolution photon sources to energy-select ions in narrow energy distributions, by the following mechanism:…”

Section: The C 3 H 7 + Appearance Energy From 2-iodopropane and 2-chlmentioning

confidence: 99%

“…There are several different experimental photoionization methods that measure the energy associated with Reaction (3). These are in order of increasing complexity, PI, threshold photoelectron photoion coincidence (TPEPICO), 9 pulsed field ionized-PEPICO (PFI-PEPICO), 10 and the related mass analyzed threshold ionization (MATI) 11 methods.…”

Section: Introductionmentioning

confidence: 99%

The C₃H₇⁺ Appearance Energy from 2-Iodopropane and 2-Chloropropane Studied by Threshold Photoelectron Photoion Coincidence

Brooks

Lau

et al. 2004

Eur J Mass Spectrom (Chichester)

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The dissociation onset for halogen atom loss was investigated for 2-iodo and 2-chloropropane ions using a newly developed threshold photoelectron photoion coincidence (TPEPICO) technique that suppresses the effects of hot electrons. This study was undertaken in order to resolve current discrepancies concerning these onsets in the literature. The 0 K dissociation thresholds were determined to be 9.818 ± 0.010 and 11.036 ± 0.010 eV for 2-C 3 H 7 I and 2-C 3 H 7 Cl, respectively. These numbers agree quite well with photoionization and a mass analyzed threshold ionization (MATI) study, but are significantly lower than onsets measured by the much higher resolution pulsed field ionization PEPICO method. The derived C 3 H 7 + heat of formation at 298 K is 803.9 ± 1.5 kJ mol-1 , and a more precise value for the 298 K 2-iodopropane heat of formation is-40.8 ± 1.3 kJ mol-1. The derived proton affinity of propene is 746.1 kJ mol-1. We have also performed a high-level ab initio calculation on the 0 K dissociation limit, E 0 , for C 3 H 7 + from C 3 H 7 Cl at the CCSD(T)/CBS level of theory with high-level corrections. The theoretical prediction of 11.048-11.061 eV for E 0 (C 3 H 7 +) from C 3 H 7 Cl is found to be consistent with the current experimental value.

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Vacuum-ultraviolet mass-analyzed threshold ionization spectra of iodobutane isomers: Conformer-specific ionization and ion-core dissociation followed by ionization

Cited by 21 publications

References 25 publications

Femtosecond photoelectron circular dichroism of chemical reactions

Femtosecond photoelectron circular dichroism of chemical reactions

Oxidation of Alkyl Ions, C_nH₂_n₊₁⁺ (n = 1−5), in Reactions with O₂ and O₃ in the Gas Phase

The C₃H₇⁺ Appearance Energy from 2-Iodopropane and 2-Chloropropane Studied by Threshold Photoelectron Photoion Coincidence

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Vacuum-ultraviolet mass-analyzed threshold ionization spectra of iodobutane isomers: Conformer-specific ionization and ion-core dissociation followed by ionization

Cited by 21 publications

References 25 publications

Femtosecond photoelectron circular dichroism of chemical reactions

Femtosecond photoelectron circular dichroism of chemical reactions

Oxidation of Alkyl Ions, CnH2n+1+ (n = 1−5), in Reactions with O2 and O3 in the Gas Phase

The C3H7+ Appearance Energy from 2-Iodopropane and 2-Chloropropane Studied by Threshold Photoelectron Photoion Coincidence

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Oxidation of Alkyl Ions, C_nH₂_n₊₁⁺ (n = 1−5), in Reactions with O₂ and O₃ in the Gas Phase

The C₃H₇⁺ Appearance Energy from 2-Iodopropane and 2-Chloropropane Studied by Threshold Photoelectron Photoion Coincidence