A Scanning Tunneling Microscope for Undergraduate Laboratories

Sears, R. K.; Orr, Betsy; Sanders, Tracey

doi:10.1063/1.4822930

Cited by 5 publications

(6 citation statements)

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“…Spectra of band 1 1 0 were not observed because of nearly zero Franck-Condon factor. 26 Line positions of B 2 AЈ -X 2 AЈ 2 1 0 and 3 1 0 were calculated using the program ASYTOP 27,28 with parameters from Brown et al 29,30 and Johns et al; 31 assignments were made accordingly. Figure 1 shows a spectrum of the transition B 2 AЈ -X 2 AЈ 3 1 0 for nascent HCO from propenal on photolysis at 193 nm near the bandhead and in the region of low frequencies; in this region transitions to states with high J are located.…”

Section: Resultsmentioning

confidence: 99%

Production of HCO from propenal photolyzed at 193 nm: Relaxation of excited states and distribution of internal states of fragment HCO

Kao

Chen

et al. 2001

The Journal of Chemical Physics

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The dynamics of photodissociation of propenal at 193 nm are studied by detecting laser-induced fluorescence of nascent fragment HCO in its transition B 2 AЈ -X 2 AЈ. Rotational states up to N ϭ30 and Kϭ3 of HCO X 2 AЈ are populated and vibrational states ͑000͒, ͑010͒, and ͑001͒ are detected. The K a ϭ1 doublet states and the two spin states for all vibrational levels detected are nearly equally populated. Much less rotational excitation is observed than the distributions calculated on a statistical model-phase space theory. This implies that dissociation occurs from the triplet channel with a small exit barrier. Small rotational excitation arises from the repulsive part of the exit barrier and the geometry of the transition state on the triplet surface. Experimental data yield an energy partitioning with translation, rotation, and vibration of HCO at 3.0, 1.3, and 1.5 kcal/mol, respectively, in total accounting for 11.5% of available energy. These results indicate that the other fragment C 2 H 3 has 3.2 kcal/mol of translation and 42.5 kcal/mol of internal energy; hence, most C 2 H 3 is expected to undergo secondary dissociation to C 2 H 2 and H. Because the appearance of HCO is faster than that calculated based on the Rice-Ramsperger-Kassel-Marcus theory, other decay pathways dominate the pathway of the radical channel from the triplet surface.

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Section: Resultsmentioning

confidence: 99%

Production of HCO from propenal photolyzed at 193 nm: Relaxation of excited states and distribution of internal states of fragment HCO

Kao

Chen

et al. 2001

The Journal of Chemical Physics

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“…The large range of N 00 (up to ¾20) and K a 00 D 0, 1, 2 yields accurate A, B and C rotational and centrifugal distortion constants. The relative intensities of the simulated spectrum are computed by taking into account the transition moments calculated by ASYTOP 20,21 and considering the square dependence of the TC-RFWM signal on the population and the two dipole moments of the transitions involved. 27 Discrepancies arise mainly because the geometric factors 27 that depend on the polarization of the electric fields and the total angular momentum are not included in the calculation.…”

Section: Procedures To Obtain Tc-rfwm Sep Spectra Of Hcomentioning

confidence: 99%

Stimulated emission pumping by two‐color resonant four‐wave mixing: rotational characterization of vibrationally excited HCO (X̃²A′)

Radi

Tulej

Knopp

et al. 2003

J Raman Spectroscopy

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Stimulated emission pumping by applying two-color resonant four-wave mixing was used to measure rotationally resolved spectra of the HCO (0,0,0)B 2 A -.0, 3, 1/X 2 A transition. The formyl radical is produced by photodissociation of formaldehyde at 31710.8 cm −1 under thermalized conditions in a low-pressure cell. In contrast to the highly congested one-color spectrum of HCO at room temperature, the double-resonance method yields well isolated transitions which are assigned unambiguously owing to intermediate level labeling. Eighty-nine rotational transitions were assigned and yield accurate rotational constants for the vibrationally excited (0,3,1) band of the electronic ground stateX 2 A of HCO. The determined rotational constant A = 25.84 ± 0.01 cm −1 is considerably higher than that for the vibrationless ground state and reflects the structural change due to excitation of the bending mode of the formyl radical.

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“…The effective Hamiltonian used to fit the ground and excited state energy levels was 16 HϭH rot ϩH cd ϩH sr ͑3͒…”

Section: B Rotational Analysismentioning

confidence: 99%

The electronic spectroscopy and molecular structure of the HPCl free radical: A potential III–V semiconductor growth intermediate

Tackett

Evans

et al. 2003

The Journal of Chemical Physics

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Articles you may be interested inThe complex spectrum of a "simple" free radical: The A ̃ -X ̃ band system of the jet-cooled boron difluoride free radical J. Chem. Phys. 135, 094305 (2011); 10.1063/1.3624528The ground state energy levels and molecular structure of jet-cooled HGeCl and DGeCl from single vibronic level emission spectroscopyPulsed discharge jet spectroscopy of DSiF and the equilibrium molecular structure of monofluorosilyleneThe Ã 2 AЈ -X 2 AЉ electronic spectra of jet-cooled HPCl and DPCl have been obtained for the first time using the pulsed electric discharge technique with a precursor mixture of PCl 3 and H 2 or D 2 . From a combination of laser-induced fluorescence and wavelength resolved emission spectra, all of the vibrational frequencies in the ground and excited states of both isotopomers have been measured and vibrational force fields have been determined. Rotational analyses of the 0 0 0 bands of both isotopomers showed small doublet splittings characteristic of an asymmetric top molecule with a single unpaired electron. From the rotational constants and the force fields, estimated equilibrium structures were derived with rЉ(PH)ϭ1.4158 (23) Å, rЉ(PCl)ϭ2.0388(23) Å, Љϭ95.02(27)°, and rЈ(PH)ϭ1.4067(20) Å, rЈ(PCl)ϭ2.0050(2) Å, and Јϭ115.53(12)°. The experimental data firmly establish that the observed spectra and those previously obtained by chemiluminescence techniques ͓Bramwell et al., Chem. Phys. Lett. 331, 483 ͑2000͔͒ are due to the HPCl free radical.

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A Scanning Tunneling Microscope for Undergraduate Laboratories

Cited by 5 publications

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Production of HCO from propenal photolyzed at 193 nm: Relaxation of excited states and distribution of internal states of fragment HCO

Production of HCO from propenal photolyzed at 193 nm: Relaxation of excited states and distribution of internal states of fragment HCO

Stimulated emission pumping by two‐color resonant four‐wave mixing: rotational characterization of vibrationally excited HCO (X̃²A′)

The electronic spectroscopy and molecular structure of the HPCl free radical: A potential III–V semiconductor growth intermediate

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A Scanning Tunneling Microscope for Undergraduate Laboratories

Cited by 5 publications

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Production of HCO from propenal photolyzed at 193 nm: Relaxation of excited states and distribution of internal states of fragment HCO

Production of HCO from propenal photolyzed at 193 nm: Relaxation of excited states and distribution of internal states of fragment HCO

Stimulated emission pumping by two‐color resonant four‐wave mixing: rotational characterization of vibrationally excited HCO (X̃2A′)

The electronic spectroscopy and molecular structure of the HPCl free radical: A potential III–V semiconductor growth intermediate

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Stimulated emission pumping by two‐color resonant four‐wave mixing: rotational characterization of vibrationally excited HCO (X̃²A′)