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You searched for subject:(isotopic substitution). Showing records 1 – 3 of 3 total matches.

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1. Wezka, Kamil. Pressure induced structural transformations of network forming glasses.

Degree: PhD, 2013, University of Bath

The method of in situ high pressure neutron diffraction was employed to measure reliable diffraction patterns to help illuminate the density-driven structural transformations in GeO2, SiO2, B2O3 and GeSe2 glass. The majority of this neutron diffraction work employed the diffractometer D4c at the ILL with a Paris-Edinburgh press which enabled the pressure range from ambient to 8 GPa to be accessed. In the cases of GeO2 and GeSe2 glass, the neutron diffraction with isotopic substitution (NDIS) protocol was developed to provide benchmark experimental results to test the results obtained from various molecular dynamics simulations using different theoretical schemes. For GeO2 glass, from a combination of neutron diffraction and molecular dynamics results, it was found that the increase in density of the glass initially occurs through a reorganisation of corner-shared GeO4 tetrahedra on an intermediate length scale as the pressure is increased from ambient to 5 GPa. At higher pressures, there is a progression from a tetrahedral to an octahedral glass, via the formation of 5-fold coordinated Ge atoms which have a predominantly square pyramidal geometry. In the work on SiO2 and B2O3 glass the pressure range for the in situ high pressure neutron diffraction results was extended to 14.5 GPa and 17.5 GPa, respectively, by using the PEARL diffractometer at ISIS. For both materials the neutron diffraction results provide complementary information to pressure x-ray diffraction studies helping to elucidate the mechanism of network collapse. In the case of SiO2 glass, densification over the measured pressure range occurs predominantly by a reorganisation of corner shared SiO4 tetrahedra on an intermediate length scale. In the case of B2O3 glass, the B-O coordination number changes from 3 to ∼ 3.9 at the pressure is increased from ∼ 8 to 17.5 GPa. For GeSe2 glass, from a combination of neutron diffraction and molecular dynamics results, it was found that the density increase from ambient pressure up ∼ 8 GPa occurs by a reorganisation of both corner and edge-sharing GeSe4 tetrahedra on an intermediate length scale. Above this pressure, 5- and 6-fold coordinated Ge atoms start to form at a similar density and homopolar bonds play an intimate role in the formation of these higher coordinated polyhedra.

Subjects/Keywords: 539; amorphous materials under pressure; isotopic substitution; polyamorphism

…2.5 Isotopic substitution in neutron diffraction for pressure experiments . . . 12 2.6 X… …Suitable experimental methods include neutron diffraction with isotopic substitution (NDIS… …β α r2 = 4πρcβ gαβ (r)r2 dr (2.23) r1 2.5 Isotopic substitution… …the Sαβ (Q) functions requires the measurement of m samples with different isotopic… …structure factors F1 (Q) and F2 (Q) are measured, where the isotopic… 

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APA (6th Edition):

Wezka, K. (2013). Pressure induced structural transformations of network forming glasses. (Doctoral Dissertation). University of Bath. Retrieved from https://researchportal.bath.ac.uk/en/studentthesis/pressure-induced-structural-transformations-of-network-forming-glasses(d8a12d01-7c77-4372-b2ea-beff54273aca).html ; https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.608339

Chicago Manual of Style (16th Edition):

Wezka, Kamil. “Pressure induced structural transformations of network forming glasses.” 2013. Doctoral Dissertation, University of Bath. Accessed October 28, 2020. https://researchportal.bath.ac.uk/en/studentthesis/pressure-induced-structural-transformations-of-network-forming-glasses(d8a12d01-7c77-4372-b2ea-beff54273aca).html ; https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.608339.

MLA Handbook (7th Edition):

Wezka, Kamil. “Pressure induced structural transformations of network forming glasses.” 2013. Web. 28 Oct 2020.

Vancouver:

Wezka K. Pressure induced structural transformations of network forming glasses. [Internet] [Doctoral dissertation]. University of Bath; 2013. [cited 2020 Oct 28]. Available from: https://researchportal.bath.ac.uk/en/studentthesis/pressure-induced-structural-transformations-of-network-forming-glasses(d8a12d01-7c77-4372-b2ea-beff54273aca).html ; https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.608339.

Council of Science Editors:

Wezka K. Pressure induced structural transformations of network forming glasses. [Doctoral Dissertation]. University of Bath; 2013. Available from: https://researchportal.bath.ac.uk/en/studentthesis/pressure-induced-structural-transformations-of-network-forming-glasses(d8a12d01-7c77-4372-b2ea-beff54273aca).html ; https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.608339


University of North Texas

2. Al-Share, Mohammad A. (Mohammad Abdel). Anomalous Behavior in the Rotational Spectra of the v₈=2 and the v₈=3 Vibrations for the ¹³C and ¹⁵N Tagged Isotopes of the CH₃CN Molecule in the Frequency Range 17-95 GHz.

Degree: 1990, University of North Texas

The rotational microwave spectra of the three isotopes (13CH312C15N, 12CH313C15N, and 13CH313C15N) of the methyl cyanide molecule in the v8=3, v8=2, v7=1 and v4=1 vibrational energy levels for the rotational components 1£J£5 (for a range of frequency 17-95 GHz.) were experimentally and theoretically examined. Rotational components in each vibration were measured to determine the mutual interactions in each vibration between any of the vibrational levels investigated. The method of isotopic substitution was employed for internal tuning of each vibrational level by single and double substitution of 13C in the two sites of the molecule. It was found that relative frequencies within each vibration with respect to another vibration were shifted in a systematic way. The results given in this work were interpreted on the basis of these energy shifts. Large departure between experimentally measured and theoretically predicted frequency for the quantum sets (J, K=±l, ϑ=±1), Kϑ-l in the v8=3 vibrational states for the 13c and 15N tagged isotopes of CH3CN showed anomalous behavior which was explained as being due to Fermi resonance. Accidently strong resonances (ASR) were introduced to account for some departures which were not explained by Fermi resonance. Advisors/Committee Members: Roberts, James Andrew, Mackey, H. J., Sears, Raymond E., Kobe, Donald Holm, Deering, William D., Theriot, Leroy James.

Subjects/Keywords: rotational microwave spectra; vibrational energy levels; isotopic substitution; methyl cyanide; vibration-rotation interaction theory; Molecular rotation.; Vibrational spectra.

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APA (6th Edition):

Al-Share, M. A. (. A. (1990). Anomalous Behavior in the Rotational Spectra of the v₈=2 and the v₈=3 Vibrations for the ¹³C and ¹⁵N Tagged Isotopes of the CH₃CN Molecule in the Frequency Range 17-95 GHz. (Thesis). University of North Texas. Retrieved from https://digital.library.unt.edu/ark:/67531/metadc330976/

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Chicago Manual of Style (16th Edition):

Al-Share, Mohammad A (Mohammad Abdel). “Anomalous Behavior in the Rotational Spectra of the v₈=2 and the v₈=3 Vibrations for the ¹³C and ¹⁵N Tagged Isotopes of the CH₃CN Molecule in the Frequency Range 17-95 GHz.” 1990. Thesis, University of North Texas. Accessed October 28, 2020. https://digital.library.unt.edu/ark:/67531/metadc330976/.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

MLA Handbook (7th Edition):

Al-Share, Mohammad A (Mohammad Abdel). “Anomalous Behavior in the Rotational Spectra of the v₈=2 and the v₈=3 Vibrations for the ¹³C and ¹⁵N Tagged Isotopes of the CH₃CN Molecule in the Frequency Range 17-95 GHz.” 1990. Web. 28 Oct 2020.

Vancouver:

Al-Share MA(A. Anomalous Behavior in the Rotational Spectra of the v₈=2 and the v₈=3 Vibrations for the ¹³C and ¹⁵N Tagged Isotopes of the CH₃CN Molecule in the Frequency Range 17-95 GHz. [Internet] [Thesis]. University of North Texas; 1990. [cited 2020 Oct 28]. Available from: https://digital.library.unt.edu/ark:/67531/metadc330976/.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Council of Science Editors:

Al-Share MA(A. Anomalous Behavior in the Rotational Spectra of the v₈=2 and the v₈=3 Vibrations for the ¹³C and ¹⁵N Tagged Isotopes of the CH₃CN Molecule in the Frequency Range 17-95 GHz. [Thesis]. University of North Texas; 1990. Available from: https://digital.library.unt.edu/ark:/67531/metadc330976/

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

3. Forthomme, Damien. High Resolution Laser Spectroscopy Of Selected Molecules In The Gas Phase.

Degree: 2011, University of New Brunswick

Subjects/Keywords: strontium monomethoxide; iridium monosulfide; samarium monoxyde; molecular bond lengths; isotopic substitution; magnesium acetylide; calcium acetylide; strontium acetylide; monoacetylide; laser-induced fluorescence; high resolution; molecular spectroscopy; molecular orbitals

Isotopic relationship between molecular parameters in CaCCH and its isotopologues… …155 7.7 Isotopic relationship between molecular parameters in SrCCH and its isotopologues… 

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APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6th Edition):

Forthomme, D. (2011). High Resolution Laser Spectroscopy Of Selected Molecules In The Gas Phase. (Thesis). University of New Brunswick. Retrieved from http://hdl.handle.net/1882/35387

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Chicago Manual of Style (16th Edition):

Forthomme, Damien. “High Resolution Laser Spectroscopy Of Selected Molecules In The Gas Phase.” 2011. Thesis, University of New Brunswick. Accessed October 28, 2020. http://hdl.handle.net/1882/35387.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

MLA Handbook (7th Edition):

Forthomme, Damien. “High Resolution Laser Spectroscopy Of Selected Molecules In The Gas Phase.” 2011. Web. 28 Oct 2020.

Vancouver:

Forthomme D. High Resolution Laser Spectroscopy Of Selected Molecules In The Gas Phase. [Internet] [Thesis]. University of New Brunswick; 2011. [cited 2020 Oct 28]. Available from: http://hdl.handle.net/1882/35387.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Council of Science Editors:

Forthomme D. High Resolution Laser Spectroscopy Of Selected Molecules In The Gas Phase. [Thesis]. University of New Brunswick; 2011. Available from: http://hdl.handle.net/1882/35387

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

.