Completely general and novel expressions are presented for <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">n</tex> th-order fast or slow correlation functions, with without background contributions, from which more specialized th- second-order auto-correlation functions derived. A straightforward method obtaining CW autocorrelation measurements of picosecond pulses is then described employs an audio loudspeaker driven at 30 Hz in one arm the...

The photodissociation dynamics of CH3I and CD3I have been examined by using multiphoton ionization to probe the CH3, CD3, I(≡5 2P3/2) I*(≡I 5 2P1/2) photoproducts. parent compounds were cooled in a supersonic expansion, collimated into molecular beam, dissociated at 266 nm. For dissociation, ratio CD3(v=0)/(v=2) was estimated be about 1.1, with multiple determinations ranging from 0.47–2.1. quantum number v here denotes nascent excitation ν2 ‘‘umbrella’’ mode. Measurements CD3(v=1) (v=3)...

Machine learning (ML) is transforming all areas of science. The complex and time-consuming calculations in molecular simulations are particularly suitable for an ML revolution have already been profoundly affected by the application existing ...Read More

M. Van Gorkom and G. E. Hall, Q. Rev. Chem. Soc., 1968, 22, 14 DOI: 10.1039/QR9682200014

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTState-resolved photofragment velocity distributions by pulsed extraction time-of-flight mass spectrometryR. Ogorzalek Loo, G. E. Hall, H. P. Haerri, and L. HoustonCite this: J. Phys. Chem. 1988, 92, 1, 5–8Publication Date (Print):January 1988Publication History Published online1 May 2002Published inissue 1 January 1988https://doi.org/10.1021/j100312a002Request reuse permissionsArticle Views185Altmetric-Citations133LEARN ABOUT THESE METRICSArticle...

Photodissociation of OCS in the region from 222–248 nm has been investigated by monitoring CO and S(1D2) primary photoproducts; as well secondary production S(3P2), S(3P1), S(3P0) using fluorescence induced a tunable vacuum ultraviolet laser source based on four-wave mixing magnesium vapor. The quantum yield S(3P) was found to be 0.00±0.02 at 222 nm. Thus, contrast our preliminary report, present more detailed investigation shows that sole sulfur product appears S(1D). photofragment is...

We have investigated the photodissociation of vinyl chloride (H2CCHCl) at 193 nm using technique photofragment translational spectroscopy. The experiments were performed Chemical Dynamics Beamline Advanced Light Source and used vacuum ultraviolet synchrotron radiation for product photoionization. observed five primary dissociation channels following an initial π*←π excitation. majority Cl atoms originate from excited-state dissociation. remaining are consistent with competition on ground...

Final state resolved vector properties of the reaction H (2S)+O2(3Σ−g)→OH(2Π)+O(3P) have been measured using Doppler spectroscopy. Velocity-aligned atoms were generated by photodissociation H2S with linearly polarized ArF excimer laser light. The correlated velocity and angular momentum distribution nascent OH products was probed induced fluorescence. Techniques are described for analyzing line shapes, modeling bipolar moments as parametric functions scattering angle. Distinctive...

The alignment of the CN fragment following dissociation ICN has been measured as a function wavelength by varying polarization tunable laser used for relative to that laser-induced fluorescence detection product. results show angular momentum vector rotor is aligned predominantly perpendicular axis laser, in agreement with expectation parallel absorption ICN. However, degree not perfect. most plausible explanation appears be occurs via transition mixture and components. Alternate...

J. T. Braunholtz, G. E. Hall, F. Mann and N. Sheppard, Chem. Soc., 1959, 868 DOI: 10.1039/JR9590000868

A new technique has been developed for determination of the projection a photofragment's angular momentum vector, J, onto its recoil velocity v. Doppler-profile spectroscopy is used in conjunction with laser-induced fluorescence probing by polarized light. The illustrated measurements CO Doppler profile following photodissociation OCS at 222 nm.

The photodissociation of glyoxal has been investigated by monitoring the CO internal energy distribution using tunable vacuum ultraviolet laser-induced fluorescence on A←X system. Appearance times for are in excellent agreement with decay times, indicating that there is no long-lived intermediate dissociation. quantum yield production independent K number describing rotation. formed almost entirely v=0 but spread over a broadly excited rotational peaking at J≂42. Analysis Doppler profiles...

Cross sections for v=0→1, 2, 3 excitation in I2+He collisions have been measured over the kinetic energy range from threshold to 0.4 eV by means of a new experimental technique which pulsed molecular beams are crossed at variable intersection angle and scattered products state selectively detected laser induced fluorescence. The values cross about 0.2 Å2 v=1 10−5 v=3 low-energy detection limit. dependences exciting v=1, approximately linear, quadratic, cubic, respectively. compared with...

Pathways, energetics, and mechanisms of the 193 nm photodissociation acetyl cyanide (CH3COCN) have been investigated using high-resolution transient frequency modulation (FM) spectroscopy photofragment translational spectroscopy. Vibrational rotational state distributions CN fragments measured by FM are in good agreement with previous work. The quantum yield is found to be 0.9 ± 0.2. State-dependent energy nonstatistical. laboratory-frame anisotropy both velocity angular momentum vanishingly...

A technique has been developed for determining the angular correlation between a photofragment’s momentum vector J, its recoil velocity v, and transition dipole moment of parent molecule μp . Doppler profile spectroscopy used in conjunction with laser-induced fluorescence probing by polarized light can be to determine correlations. The pairwise correlations these vectors as well their triple are discussed limiting cases using classical approach general case quantum based on density matrices....

Explicitly time-dependent implementations of optical frequency modulation spectroscopy have been recently applied to a wide range problems in chemical physics. We provide brief description the methodology, with an emphasis on its intrinsic advantages for interrogating transient species. Several examples highlight application technique high-resolution absorption spectra free radicals, rate measurements gas-phase reactions, and Doppler products photoinitiated reactions.

We have performed photodissociation experiments on CHBr3 at 248 nm using VUV ionization photofragment translational spectroscopy. Prompt C−Br bond fission is the dominant single-photon dissociation channel. In addition to primary Br and CHBr2 signals, we observe Br, CHBr, CBr, HBr, Br2 products attributed secondary of CHBr. There are three competing fragmentation channels from CHBr2: CHBr + CH Br2, CBr HBr. The conclusion that fragments do not arise a channel in appreciable yield supported...

Diode laser transient absorption/gain spectroscopy is used to monitor time-dependent populations of CD3 fragments formed in the photodissociation acetone-d6 at 193 nm. Selected rotational lines have been measured ν2 ‘‘umbrella’’ fundamental and first two hot bands, ν3 asymmetric stretching band. Substantial growth observed vibrationless state on time scale vibrational relaxation. We estimate that only about 15% nascent population states we detect: ν2=1 2, ν3=1, state. Most methyl evidently...

Nascent Doppler profiles of CN (X 2∑+) fragments from the à band photodissociation room temperature ICN have been measured using high-resolution transient frequency modulated absorption spectroscopy. Results for dissociation at 222 nm, 248 266 and 308 nm are presented. From multiple states, we determine branching ratios coincident atomic iodine bipolar moments characterizing velocity angular momentum anisotropy. The measurements provide sensitive tests strengths optical coupling to excited...

We present a method for recovering Doppler broadened absorption line shapes from frequency modulated (FM) spectra. The of analysis is calibrated and demonstrated with thermalized CN radicals produced by photodissociation cyanogen (NCCN), probed on the A–X system near 800 nm Ti: sapphire ring laser. Nonthermal, lines translationally nascent photofragments can also be recovered direct transformations experimental FM profiles acquired time resolution exceeding 100 ns. superior signal-to-noise...

The resonance enhanced multiphoton ionization time-of-flight (REMPI-TOF) technique was applied to study the complex dissociation of CF2I2 in a supersonic expansion. Using nanosecond excitation at 248, 266, and 304 nm probing I3/2 and/or I1/2 photoproducts, we determined photofragment speed distribution, recoil anisotropy parameter β branching ratio for each decay channels. At 248 proceeds according concerted three-body decay, CF2I2→hvCF2+I1/2+I3/2 (90%) or CF2I2→hvCF2+I3/2+I3/2 (10%)...

We report the use of time-resolved frequency modulation (FM) spectroscopy for measurement photochemically generated radicals. CN radicals from 193 nm photodissociation cyanogen (NCCN) have been detected using a phase-modulated cw Ti:sapphire ring laser, probing single rotational lines A 2Π←X 2Σ system. The combination sensitivity with time and resolution is more than adequate to record Doppler-broadened line shapes collisionless photofragments. Significant signal-to-noise enhancement...

Correlations between either scalar or vector quantities measured in the study of photodissociation dynamics can serve to provide a very detailed picture dissociative event. This article discusses use Doppler profile and time-of-flight spectroscopy learn about correlation separate internal energies two recoiling fragments, way which energy distribution fragment varies with its recoil direction determine angle photofragment's velocity rotation vector. Two new techniques are introduced....

We report measurements of the kinetic energy dependence v=0→1 vibrational excitation cross section for He+12 collisions. These results were obtained with a new crossed, pulsed molecular beam apparatus having variable interaction angle and laser-induced fluorescence detection. The shows sharp onset at threshold, rises nearly linearly increasing to highest experimental value energy, about 13 times quantum. At higher energies, v=0→2 is also observed. data constitute first microscopic...