Investigation of Time-Dependent Phenomena by Use of Step-Scan FT-IR

Palmer, Richard A.; Ji, Chao; Dittmar, Rebecca M.; Gregoriou, Vasilis G.; Plunkett, Susan E.

doi:10.1366/0003702934067568

Cited by 122 publications

(49 citation statements)

References 74 publications

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“…Early work on small systems, including 12 Recent advances in ultrafast lasers, including the development of Ti:Sapphire oscillators, regenerative amplifiers and qptical parametric amplifiers, have made the generation of 100 fs infrared pulses possible. The move from visible spectroscopy t o infrared spectroscopy is extremely important in chemistry, since the infrared region of the spectrum allows much better deduction of structural information.…”

Section: Chapter 1 Introductionmentioning

confidence: 99%

Time resolved infrared studies of C-H bond activation by organometallics

Asplund¹

1998

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' Lhe Govermient reserves for itself and others acting on its behalf a ruyalty free, nonexclusive, irrev-le, world-wide license for governmental purpses to publish, distribute, translate, duplicate, exhibit, and perform a q such data aopyrighted by the amtractor.The U.S. Department of Energy has the right to use this document for any purpose whatsoever, including the right to reproduce all or any part thereof. Much of the study of these C-H activation reactions has focussed on the spectroscopy of the CO ligands. We have shown the spectroscopy of several non-CO modes in the system. Spectroscopy of the Rh-H stretch at 2080 cm-lhas allowed for the unambiguous assignment of the time scale of final C-H bond breaking step.

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Section: Chapter 1 Introductionmentioning

confidence: 99%

Time resolved infrared studies of C-H bond activation by organometallics

Asplund¹

1998

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“…A second, faster, modulation, independent of the interferometer scanning, can therefore be introduced and used as the signal carrier. [6][7][8] This second modulation can be induced in the sample itself, as in polymer rheo-optical studies. 6,7 For photoacoustic spectroscopy, it is best to modulate the infrared beam via phase modulation, 6,8 in which an interferometer mirror dithers to oscillate the retardation about the set point of each interferometer step.…”

Section: Introductionmentioning

confidence: 99%

Quantitative Depth Profiling of Layered Samples Using Phase-Modulation FT-IR Photoacoustic Spectroscopy

Jones

McClelland

1996

Appl Spectrosc

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In phase-modulation FT-IR spectroscopy, all wavelengths in a spectrum are modulated at the same frequency and in phase. This factor makes the use of photoacoustic phase data for depth profiling samples much easier in phase modulation than in rapid scan. A method to quantitatively measure layer thickness by using the phase of a substrate spectrum peak is demonstrated with a series of samples consisting of thin polymer films on substrates. Additions to the basic method are demonstrated that extend its application to cases where the substrate peak is overlapped by a spectrum peak of the surface film. A linear relationship between phase angle and layer thickness extending to thicknesses greater than twice the thermal diffusion length is demonstrated. Representations of phase modulation data as a family of angle-specific spectra, as magnitude vs. phase curves, and as a power spectrum and phase spectrum pair, each of which is useful for different aspects of depth profiling, are discussed. Calculating these representations from a single pair of orthogonal interferograms is described. In phase-modulation FT-IR spectroscopy, all wavelengths in a spectrum are modulated at the same frequency and in phase. This factor makes the use of photoacoustic phase data for depth profiling samples much easier in phase modulation than in rapid scan. A method to quantitatively measure layer thickness by using the phase of a substrate spectrum peak is demonstrated with a series of samples consisting of thin polymer films on substrates. Additions to the basic method are demonstrated that extend its application to cases where the substrate peak is overlapped by a spectrum peak of the surface film. A linear relationship between phase angle and layer thickness extending to thicknesses greater than twice the thermal diffusion length is demonstrated. Representations of phase modulation data as a family of angle-specific spectra, as magnitude vs. phase curves, and as a power spectrum and phase spectrum pair, each of which is useful for different aspects of depth profiling, are discussed. Calculating these representations from a single pair of orthogonal interferograms is described. Keywords

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“…The FTIR was performed in a step-scan mode, with which the movable mirror of the interferometer can be moved step-by-step. [17][18][19][20][21] In this work, the digitized signals which were repeatedly collected for 30 laser shots were monitored with a InSb detector cooled at 77 K, followed by a preamplifier. The detector and the preamplifier had the response time of ∼700 and ∼200 ns, respectively.…”

Section: Methodsmentioning

confidence: 99%

Gas-phase photodissociation of CH3COCN at 308 nm by time-resolved Fourier-transform infrared emission spectroscopy

Yeh

Chao

Tsai

et al. 2012

The Journal of Chemical Physics

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By using time-resolved Fourier-transform infrared emission spectroscopy, the fragments of HCN(v = 1, 2) and CO(v = 1-3) are detected in one-photon dissociation of acetyl cyanide (CH(3)COCN) at 308 nm. The S(1)(A(")), (1)(n(O), π(∗) (CO)) state at 308 nm has a radiative lifetime of 0.46 ± 0.01 μs, long enough to allow for Ar collisions that induce internal conversion and enhance the fragment yields. The rate constant of Ar collision-induced internal conversion is estimated to be (1-7) × 10(-12) cm(3) molecule(-1) s(-1). The measurements of O(2) dependence exclude the production possibility of these fragments via intersystem crossing. The high-resolution spectra of HCN and CO are analyzed to determine the ro-vibrational energy deposition of 81 ± 7 and 32 ± 3 kJ∕mol, respectively. With the aid of ab initio calculations, a two-body dissociation on the energetic ground state is favored leading to HCN + CH(2)CO, in which the CH(2)CO moiety may further undergo secondary dissociation to release CO. The production of CO(2) in the reaction with O(2) confirms existence of CH(2) and a secondary reaction product of CO. The HNC fragment is identified but cannot be assigned, as restricted to a poor signal-to-noise ratio. Because of insufficient excitation energy at 308 nm, the CN and CH(3) fragments that dominate the dissociation products at 193 nm are not detected.

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Investigation of Time-Dependent Phenomena by Use of Step-Scan FT-IR

Cited by 122 publications

References 74 publications

Time resolved infrared studies of C-H bond activation by organometallics

Time resolved infrared studies of C-H bond activation by organometallics

Quantitative Depth Profiling of Layered Samples Using Phase-Modulation FT-IR Photoacoustic Spectroscopy

Gas-phase photodissociation of CH3COCN at 308 nm by time-resolved Fourier-transform infrared emission spectroscopy

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