A pulsed discharge source of transients for matrix isolation spectroscopy

Thoma, A.; Wurfel, Brent E.; Schlachta, Richard; Lask, G.; Bondybey, V. E.

doi:10.1021/j100197a019

Cited by 45 publications

(17 citation statements)

References 7 publications

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“…'~~'~ The NOlrare gas matrices were formed by means of our pulsed supersonic expansion deposition technique. 19 To generate the ionic species, the self-igniting dc discharge through the expanding gas was used.20 The experimental setup for obtaining the ZEKE spectra was also described p r e v i~u s l y .~,~~ For these experiments, an improved apparatus, using a home-built piezoelectric valve was employed. A pulsed supersonic expansion through a mixture of 5% NO in 20 bar of neon provided a strong, stable NO dimer beam.…”

Section: Methodsmentioning

confidence: 99%

Identification, Structure, and Vibrational Assignment of the NO Dimer Cation

Strobel¹,

Knoblauch²,

Agreiter³

et al. 1995

J. Phys. Chem.

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We have reinvestigated the NO dimer cation, (NO)*+, both in the gas phase by high-resolution zero kinetic energy-pulsed field ionization (ZEKE-PFI) photoelectron spectroscopy and by infrared absorption spectroscopy in a solid neon matrix. Comparison of the results leads to the conclusion that the matrix infrared absorption bands previously assigned to the anion are actually due to the NO dimer cation. This reassignment also implies that the cation has a centrosymmetric trans structure. IntroductionThe oxides of nitrogen, as well as the corresponding cations, are compounds of considerable theoretical and practical interest. The most common oxides, NO and NOz, possess an unpaired electron and are therefore strictly speaking free radicals. They are both quite reactive and readily form complexes. Gaseous NO2 is at lower temperatures and higher pressures almost completely dimerized, and also NO forms dimers easily. Compared with other components of the atmosphere, the oxides of nitrogen also have very low ionization potentials, and the corresponding cations are of considerable importance for the ionic chemistry of the earth'sOzf and NO+ are the dominant ions in the thermosphere above 90 km height, with the former being converted into the latter by the reactionAt an altitude of about 85-90 km the pressure becomes high and the translational temperature low enough for three body complex stabilization, and the NO+ is converted into complex and cluster ions of the type NOf*X with X = COz, N2, and H20. These then undergo a series of ligand exchange reactions and are converted mainly into solvated protons.'a6As a part of the study of the clusters and complexes of NO and NO+, we have investigated in our laboratory the corresponding NO dimer and its ~a t i o n .~ The neutral dimer has previously been rather extensively studied and is fairly well known.8 It is characterized by an uncommonly long N-N bond and a cis-planar structure9 (CzV symmetry). The photodissociation of the cation has been studied,1° and some of its properties can be obtained from the (N0)2 vacuum-ultraviolet (W) photoionization and photoelectron spectra.' '- 13 We have recently recorded high-resolution zero kinetic energy-pulsed field ionization (ZEKE-PFI)14 photoelectron spectra of the dimer.' Analysis of the vibrational structure led us to the conclusion that the cation must have a geometry considerably different from that of the neutral, and we have suggested a nonplanar gauche geometry.The NO dimer15 and its ionic counterpart^^^^'^ have also been extensively studied in low-temperature matrices. Andrews and co-workers16 have originally identified a band at about 1593 cm-l as trans-(NO)z-in an Ar matrix when they discharged a NzO/Ar mixture in a Townsend source. Recently, Jacox and Thornps~n'~ have ionized Ne matrices containing NO using photoionization and Penning ionization from Ne* and assigned a band appearing in the photolyzed matrices at 1619.2 cm-' to the asymmetric stretching mode, v4, of the NO dimer union. @ Abstract published in Advance ACS Abs...

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Section: Methodsmentioning

confidence: 99%

Identification, Structure, and Vibrational Assignment of the NO Dimer Cation

Strobel¹,

Knoblauch²,

Agreiter³

et al. 1995

J. Phys. Chem.

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“…CP-FTMW spectroscopy is a comparatively recent addition to a long list of spectroscopic techniques that have been applied to study molecules and complexes generated in this way. [31][32][33][34] Fourier transform microwave spectroscopy (using either BF-or CP-FTMW spectrometers) can generally be performed at high resolution such that transitions are recorded with typical FWHM (full width at half maximum) of less than 150 kHz. This high resolution greatly assists the unambiguous assignment of spectra to carrier molecules and facilitates highly accurate determination of molecular geometries.…”

Section: Exploiting Plasma Chemistry To Generate Novel Molecules and mentioning

confidence: 99%

A perspective on chemistry in transient plasma from broadband rotational spectroscopy

Zaleski

Stephens

Walker

2014

Phys. Chem. Chem. Phys.

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Broadband rotational spectroscopy provides a new method by which plasma chemistry can be explored. Molecules and complexes form when precursors within an expanding gas sample are allowed to interact with plasma generated by an electrical discharge or laser vaporisation of a solid. It is thus possible to selectively generate specific molecules or complexes for study through a careful choice of appropriate precursors. It is also possible to survey an extensive range of the products formed under a given set of initial conditions in an approach termed "broadband reaction screening". Broadband rotational spectroscopy provides an opportunity to simultaneously monitor the transitions of many different chemical products and this allows broader details of reaction pathways to be inferred. This Perspective will describe various experimental approaches and review recent works that have applied broadband rotational spectroscopy to study molecules and complexes generated (in whole or in part) through chemistry occurring within transient plasma.

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“…This mixture was deposited onto the cold window held at ϳ8 K using the pulsed deposition technique. [43][44][45][46] Typical conditions were as follows: 1 ms pulse duration, 10 Hz repetition rate, and 2 h deposition time.…”

Section: A Matrix Isolation Experimentsmentioning

confidence: 99%

Characterization of iso-CF2I2 in frequency and ultrafast time domains

El‐Khoury

George

Kalume

et al. 2010

The Journal of Chemical Physics

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The photolysis of diiododifluoromethane (CF(2)I(2)) in condensed phases was studied by a combination of matrix isolation and ultrafast time-resolved spectroscopy, in concert with ab initio calculations. Photolysis at wavelengths of 355 or 266 nm of CF(2)I(2):Ar samples (1:5000) held at approximately 8 K yielded iso-CF(2)I(2) (F(2)C-I-I), a metastable isomer of CF(2)I(2), characterized here for the first time. The infrared (IR) spectra of this isomer were recorded in matrix experiments, and the derived positions of the C-F stretching modes are in very good agreement with the predictions of high level ab initio calculations, which show that the iso-form is a minimum on the CF(2)I(2) ground state potential energy surface. The formation of this isomer following 350 nm excitation of CF(2)I(2) in room temperature CCl(4) solutions was monitored through its intense C-F stretching mode by means of ultrafast time-resolved IR absorption. Together, matrix isolation and ultrafast IR absorption experiments suggest that the formation of iso-CF(2)I(2) occurs via recombination of CF(2)I radical and I atom. Ultrafast IR experiments detect a delayed rise of iso-CF(2)I-I absorption, placing an upper limit of 400 fs for the C-I bond dissociation and primary geminate recombination processes. The product absorption spectrum recorded 1 ns after 350 nm excitation of CF(2)I(2) in solution is virtually identical to the visible absorption spectrum of iso-CF(2)I(2) trapped in matrix isolation experiments [with subtracted I(2)(X) absorption]. The formation of this isomer in solution at room temperature has direct dynamic implications for the ultrafast production of molecular iodine from electronically excited CF(2)I(2).

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A pulsed discharge source of transients for matrix isolation spectroscopy

Cited by 45 publications

References 7 publications

Identification, Structure, and Vibrational Assignment of the NO Dimer Cation

Identification, Structure, and Vibrational Assignment of the NO Dimer Cation

A perspective on chemistry in transient plasma from broadband rotational spectroscopy

Characterization of iso-CF2I2 in frequency and ultrafast time domains

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