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Jaan Laane - One of the best experts on this subject based on the ideXlab platform.
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gas phase raman spectra and the Potential Energy Function for the internal rotation of 1 3 butadiene and its isotopologues
Journal of Physical Chemistry A, 2011Co-Authors: Praveenkumar Boopalachandran, Norman C Craig, P Groner, Jaan LaaneAbstract:The gas-phase Raman spectra of 1,3-butadiene and its 2,3-d2, 1,1,4,4-d4, and -d6 isotopologues have been recorded with high sensitivity in the region below 350 cm–1 in order to investigate the internal rotation (torsional) vibration. Based on more accurate structural information, the internal rotor constants Fn were calculated as a Function of rotation angle (ϕ). The data for all the isotopologues were then fit using a one-dimensional Potential Energy Function of the form V = 1/2∑Vn(1 – cos ϕ). Initial Vn values were based on those generated from theoretical calculations. The agreement between observed and calculated frequencies is very good, although bands not taken into account were present in the spectra. The Energy difference between the trans and gauche forms was determined to be about 1030 cm–1 (2.94 kcal/mol), and the barrier between the two equivalent gauche forms was determined to be about 180 cm–1 (0.51 kcal/mol), which agrees well with high-level ab initio calculations. An alternative set of as...
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ultraviolet absorption spectra of pyridine d0 and d5 and their ring bending Potential Energy Function in the s1 n π state
Chemical Physics Letters, 2008Co-Authors: Praveenkumar Boopalachandran, Jaan LaaneAbstract:Abstract The ultraviolet absorption spectra of both pyridine and its pyridine-d 5 isotopomer have been recorded and assigned with a focus on the low-frequency vibrational modes in the S 1 (n,π ∗ ) electronic excited state. More than a dozen absorption bands associated with the ν 18 (formerly labeled ν 16b ) bending mode were observed. An Energy map for the low-frequency modes was constructed and the data for the ν 18 mode allowed a highly anharmonic one-dimensional Potential Energy Function to be determined for the S 1 excited state. In this state pyridine is quasi-planar and very floppy with a barrier to planarity of 3 cm −1 .
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vibrational spectra ab initio calculations and ring puckering Potential Energy Function for γ crotonolactone
Journal of Physical Chemistry A, 2007Co-Authors: Abdulaziz A Alsaadi, Jaan LaaneAbstract:The infrared and Raman spectra of liquid and vapor gamma-crotonolactone have been collected. Both the experimental data and ab initio calculations show that the molecule is rigidly planar in its electronic ground state. This conclusion agrees with the previously reported microwave studies and is attributed to the conjugation between the C=C and C=O double bonds of the ring. The ring-puckering Potential Energy Function was generated from ab initio calculations and was confirmed by the vapor-phase Raman spectra to be nearly harmonic. Density Functional theory (DFT) calculations predict a harmonic ring-puckering frequency of 203 cm(-1) as compared to the observed vapor-phase Raman value of 208 cm(-1). The DFT calculations were also used to compute the infrared and Raman spectra of gamma-crotonolactone, and these agree very well with the experimental spectra.
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fluorescence and ultraviolet absorption spectra and structure of coumaran and its ring puckering Potential Energy Function in the s1 π π excited state
Journal of Chemical Physics, 2006Co-Authors: Juan Yang, Jaebum Choo, Martin Wagner, Katsuhiko Okuyama, Kevin Morris, Zane Arp, Niklas Meinander, Ohyun Kwon, Jaan LaaneAbstract:The fluorescence excitation (jet cooled), single vibrational level fluorescence, and the ultraviolet absorption spectra of coumaran associated with its S1(π,π*) electronic excited state have been recorded and analyzed. The assignment of more than 70 transitions has allowed a detailed Energy map of both the S0 and S1 states of the ring-puckering (ν45) vibration to be determined in the excited states of nine other vibrations, including the ring-flapping (ν43) and ring-twisting (ν44) vibrations. Despite some interaction with ν43 and ν44, a one-dimensional Potential Energy Function for the ring puckering very nicely predicts the experimentally determined Energy level spacings. In the S1(π,π*) state coumaran is quasiplanar with a barrier to planarity of 34cm−1 and with Energy minima at puckering angles of ±14°. The corresponding ground state (S0) values are 154cm−1 and ±25°. As is the case with the related molecules indan, phthalan, and 1,3-benzodioxole, the angle strain in the five-membered ring increases upo...
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s0 ring puckering Potential Energy Function for coumaran
Journal of Physical Chemistry A, 2005Co-Authors: Juan Yang, Katsuhiko Okuyama, Kevin Morris, Zane Arp, Jaan LaaneAbstract:With the aid of a reported inversion splitting value, the far-infrared spectrum resulting from the ring-puckering vibration of coumaran has been reassigned and the one-dimensional Potential Energy ...
Juan Yang - One of the best experts on this subject based on the ideXlab platform.
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fluorescence and ultraviolet absorption spectra and structure of coumaran and its ring puckering Potential Energy Function in the s1 π π excited state
Journal of Chemical Physics, 2006Co-Authors: Juan Yang, Jaebum Choo, Martin Wagner, Katsuhiko Okuyama, Kevin Morris, Zane Arp, Niklas Meinander, Ohyun Kwon, Jaan LaaneAbstract:The fluorescence excitation (jet cooled), single vibrational level fluorescence, and the ultraviolet absorption spectra of coumaran associated with its S1(π,π*) electronic excited state have been recorded and analyzed. The assignment of more than 70 transitions has allowed a detailed Energy map of both the S0 and S1 states of the ring-puckering (ν45) vibration to be determined in the excited states of nine other vibrations, including the ring-flapping (ν43) and ring-twisting (ν44) vibrations. Despite some interaction with ν43 and ν44, a one-dimensional Potential Energy Function for the ring puckering very nicely predicts the experimentally determined Energy level spacings. In the S1(π,π*) state coumaran is quasiplanar with a barrier to planarity of 34cm−1 and with Energy minima at puckering angles of ±14°. The corresponding ground state (S0) values are 154cm−1 and ±25°. As is the case with the related molecules indan, phthalan, and 1,3-benzodioxole, the angle strain in the five-membered ring increases upo...
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s0 ring puckering Potential Energy Function for coumaran
Journal of Physical Chemistry A, 2005Co-Authors: Juan Yang, Katsuhiko Okuyama, Kevin Morris, Zane Arp, Jaan LaaneAbstract:With the aid of a reported inversion splitting value, the far-infrared spectrum resulting from the ring-puckering vibration of coumaran has been reassigned and the one-dimensional Potential Energy ...
Kevin Morris - One of the best experts on this subject based on the ideXlab platform.
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fluorescence and ultraviolet absorption spectra and structure of coumaran and its ring puckering Potential Energy Function in the s1 π π excited state
Journal of Chemical Physics, 2006Co-Authors: Juan Yang, Jaebum Choo, Martin Wagner, Katsuhiko Okuyama, Kevin Morris, Zane Arp, Niklas Meinander, Ohyun Kwon, Jaan LaaneAbstract:The fluorescence excitation (jet cooled), single vibrational level fluorescence, and the ultraviolet absorption spectra of coumaran associated with its S1(π,π*) electronic excited state have been recorded and analyzed. The assignment of more than 70 transitions has allowed a detailed Energy map of both the S0 and S1 states of the ring-puckering (ν45) vibration to be determined in the excited states of nine other vibrations, including the ring-flapping (ν43) and ring-twisting (ν44) vibrations. Despite some interaction with ν43 and ν44, a one-dimensional Potential Energy Function for the ring puckering very nicely predicts the experimentally determined Energy level spacings. In the S1(π,π*) state coumaran is quasiplanar with a barrier to planarity of 34cm−1 and with Energy minima at puckering angles of ±14°. The corresponding ground state (S0) values are 154cm−1 and ±25°. As is the case with the related molecules indan, phthalan, and 1,3-benzodioxole, the angle strain in the five-membered ring increases upo...
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s0 ring puckering Potential Energy Function for coumaran
Journal of Physical Chemistry A, 2005Co-Authors: Juan Yang, Katsuhiko Okuyama, Kevin Morris, Zane Arp, Jaan LaaneAbstract:With the aid of a reported inversion splitting value, the far-infrared spectrum resulting from the ring-puckering vibration of coumaran has been reassigned and the one-dimensional Potential Energy ...
Zane Arp - One of the best experts on this subject based on the ideXlab platform.
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fluorescence and ultraviolet absorption spectra and structure of coumaran and its ring puckering Potential Energy Function in the s1 π π excited state
Journal of Chemical Physics, 2006Co-Authors: Juan Yang, Jaebum Choo, Martin Wagner, Katsuhiko Okuyama, Kevin Morris, Zane Arp, Niklas Meinander, Ohyun Kwon, Jaan LaaneAbstract:The fluorescence excitation (jet cooled), single vibrational level fluorescence, and the ultraviolet absorption spectra of coumaran associated with its S1(π,π*) electronic excited state have been recorded and analyzed. The assignment of more than 70 transitions has allowed a detailed Energy map of both the S0 and S1 states of the ring-puckering (ν45) vibration to be determined in the excited states of nine other vibrations, including the ring-flapping (ν43) and ring-twisting (ν44) vibrations. Despite some interaction with ν43 and ν44, a one-dimensional Potential Energy Function for the ring puckering very nicely predicts the experimentally determined Energy level spacings. In the S1(π,π*) state coumaran is quasiplanar with a barrier to planarity of 34cm−1 and with Energy minima at puckering angles of ±14°. The corresponding ground state (S0) values are 154cm−1 and ±25°. As is the case with the related molecules indan, phthalan, and 1,3-benzodioxole, the angle strain in the five-membered ring increases upo...
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s0 ring puckering Potential Energy Function for coumaran
Journal of Physical Chemistry A, 2005Co-Authors: Juan Yang, Katsuhiko Okuyama, Kevin Morris, Zane Arp, Jaan LaaneAbstract:With the aid of a reported inversion splitting value, the far-infrared spectrum resulting from the ring-puckering vibration of coumaran has been reassigned and the one-dimensional Potential Energy ...
Katsuhiko Okuyama - One of the best experts on this subject based on the ideXlab platform.
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fluorescence and ultraviolet absorption spectra and structure of coumaran and its ring puckering Potential Energy Function in the s1 π π excited state
Journal of Chemical Physics, 2006Co-Authors: Juan Yang, Jaebum Choo, Martin Wagner, Katsuhiko Okuyama, Kevin Morris, Zane Arp, Niklas Meinander, Ohyun Kwon, Jaan LaaneAbstract:The fluorescence excitation (jet cooled), single vibrational level fluorescence, and the ultraviolet absorption spectra of coumaran associated with its S1(π,π*) electronic excited state have been recorded and analyzed. The assignment of more than 70 transitions has allowed a detailed Energy map of both the S0 and S1 states of the ring-puckering (ν45) vibration to be determined in the excited states of nine other vibrations, including the ring-flapping (ν43) and ring-twisting (ν44) vibrations. Despite some interaction with ν43 and ν44, a one-dimensional Potential Energy Function for the ring puckering very nicely predicts the experimentally determined Energy level spacings. In the S1(π,π*) state coumaran is quasiplanar with a barrier to planarity of 34cm−1 and with Energy minima at puckering angles of ±14°. The corresponding ground state (S0) values are 154cm−1 and ±25°. As is the case with the related molecules indan, phthalan, and 1,3-benzodioxole, the angle strain in the five-membered ring increases upo...
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s0 ring puckering Potential Energy Function for coumaran
Journal of Physical Chemistry A, 2005Co-Authors: Juan Yang, Katsuhiko Okuyama, Kevin Morris, Zane Arp, Jaan LaaneAbstract:With the aid of a reported inversion splitting value, the far-infrared spectrum resulting from the ring-puckering vibration of coumaran has been reassigned and the one-dimensional Potential Energy ...