Electronic Structure of Cage Amines: Absorption Spectra of Triethylenediamine and Quinuclidine

Halpern, Arthur M.; Roebber, J. L.; Weiss, Karl

doi:10.1063/1.1670230

Cited by 64 publications

(40 citation statements)

References 19 publications

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“…This is at least an order of magnitude larger than the observed lifetimes for the 3s states of the three previously studied amines DMIPA, DMPA and Mpyr. 1 As suggested by our calculations in Section III.C, and as also appears to be confirmed by comparing the band positions of the relevant absorption spectra, 3,4 the 3s and optically bright 3p state of ABCO sit at very similar or slightly lower energies than these other systems. The corresponding 3s-3p energy gap is also therefore very similar.…”

Section: B Decay Of the 3s Statesupporting

confidence: 85%

The effects of symmetry and rigidity on non-adiabatic dynamics in tertiary amines: a time-resolved photoelectron velocity-map imaging study of the cage-amine ABCO

Klein

Morsing

Livingstone

et al. 2016

Phys. Chem. Chem. Phys.

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The non-adiabatic relaxation dynamics of the tertiary cage-amine azabicyclo[2.2.2]octane (ABCO, also known as quinuclidine) have been investigated following 3p Rydberg excitation at 201 nm using femtosecond time-resolved photoelectron imaging (TRPEI). The aim of the study was to investigate the influence of the rigid and symmetric cage structure found in ABCO on the general non-adiabatic relaxation processes commonly seen in other tertiary aliphatic amines (TAAs). Our data is compared with TRPEI results very recently obtained for several structurally less rigid TAA systems [J. O. F. Thompson et al., Chem. Sci., 2016, 7, 1826-1839] and helps to confirm many of the previously reported findings. The experimental results for ABCO in the short-time (<1 ps) regime strongly support earlier conclusions suggesting that planarization about the N-atom is not a prerequisite for efficient 3p-3s internal conversion. Additionally, individual photoelectron peaks within our ABCO data show no temporal shifts in energy. As confirmed by our supporting quantum mechanical calculations, this demonstrates that neither internal conversion within the 3p manifold or significant conformational re-organization are possible in the ABCO system. This result therefore lends strong additional support to the active presence of such dynamical effects in other, less conformationally restricted TAA species, where photoelectron peak shifts are commonly observed. Finally, the extremely long (>1 ns) 3s Rydberg state lifetime seen in ABCO (relative to other TAA systems at similar excitation energies) serves to illustrate the large influence of symmetry and conformational rigidity on intramolecular vibrational redistribution processes previously implicated in mediating this aspect of the overall relaxation dynamics.

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Section: B Decay Of the 3s Statesupporting

confidence: 85%

The effects of symmetry and rigidity on non-adiabatic dynamics in tertiary amines: a time-resolved photoelectron velocity-map imaging study of the cage-amine ABCO

Klein

Morsing

Livingstone

et al. 2016

Phys. Chem. Chem. Phys.

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“…3a). The energy difference observed between the S 1 and S 2 photoelectron peaks is $0.5 eV, in good agreement with both frequency domain spectroscopy, 8,11,16 where two-photon spectroscopy permits the direct observation of both the S 1 and S 2 origins, and with previous ab initio computations.…”

Section: Resultssupporting

confidence: 66%

“…Much of this attention stems from the fact that DABCO is a paradigmatic example of an alkylamine: a group of molecules whose electronic structure is closely related to that of ammonia, undergoing significant geometric relaxation upon electronic excitation. 8 Initial experimental studies on the lowlying electronic states of DABCO employed absorption spectroscopy.…”

Section: Introductionmentioning

confidence: 99%

“…23 Excitation of this mode via a dipole transition is symmetry forbidden (although excitation of an even number of quanta is possible, the corresponding peaks were not observed in the S 2 absorption spectrum 8,10,16 ). We note, however, that there will be population of this low frequency mode in a Boltzmann ensemble at T $ 300-400 K. As will be seen in the next section, the S 1 electronic state in DABCO is also slightly twisted around the N-N axis, whereas the S 2 state is not.…”

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confidence: 99%

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Non-Born–Oppenheimer wavepacket dynamics in polyatomic molecules: vibrations at conical intersections in DABCO

et al. 2011

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The role of vibrational dynamics in the vicinity of conical intersections is investigated using the first two electronically excited states of 1,4-diazabicyclo[2,2,2]octane (DABCO) by combining time-resolved photoelectron spectroscopy with ab initio computation. Upon resonant excitation of the origin band of the short-lived S 2 ( 1 E 0 ) state, oscillations in the electronic population between the S 2 ( 1 E 0 ) and the S 1 ( 1 A 0 1 ) electronic states are observed with a period of $3 ps. Ab initio computations are employed to characterise these low-lying excited states, which arise from single excitations into the 3s and 3p Rydberg orbitals. Although Rydberg states are generally only weakly coupled, DABCO exhibits rapid nonadiabatic dynamics. This implies that strong coupling occurs only in the immediate vicinity of a conical intersection, enabling unique identification of those vibrations which generate the nonadiabatic transitions. To this end, seams of conical intersection are located at energetically relevant geometries, engendered by differential distortions of the S 1 and S 2 potentials due to vibronic coupling and a Jahn-Teller-distorted S 2 minimum energy point. From an analysis of the conical intersection topography, those vibrations leading to a maximal modulation of the coupling between the electronic states are readily identified. The observed oscillation in the decay of S 2 state population is thereby assigned to the beat frequency between two sets of vibronic eigenstates within the S 1 manifold, coherently prepared together with another set at the S 2 band origin, and whose nominal e 0 degeneracy is lifted due to differential coupling to the Jahn-Teller-distorted components of S 2 .

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“…For the complexes of ammonia with fluorine and chlorine, entirely reasonable interaction energies (10.4 and 21.8 kcal/mole, respectively) have been calculated at rather short equilibrium intermolecular separations [7]. More recently, the complexes of the cage-structured amines 1-azabicyclo (2,2,2)octane (ABCO) and 1,4-diazabicyclo(2,2,2)octane (DABCO) [9] with chlorine have been studied by the CNDO method I-8]. More recently, the complexes of the cage-structured amines 1-azabicyclo (2,2,2)octane (ABCO) and 1,4-diazabicyclo(2,2,2)octane (DABCO) [9] with chlorine have been studied by the CNDO method I-8].…”

Section: Introductionmentioning

confidence: 96%

π-Molecular complexes: A modified CNDO study of the benzene-borazine system

Grein

Weiss

1974

Theoret. Chim. Acta

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The standard CNDO/2 method is shown to be unable to produce meaningful potential curves for n-n-type molecular complexes. A modification of this method in which pairs of atoms associated with the same molecule and with different molecules are differentiated leads to reduced intermolecular bonding and provides reasonable stabilization energies and intermolecular separations. Calculations based on this modified method indicate that benzene-borazine and borazine-borazine complexes in which the molecules are symmetrically disposed in parallel planes can exist in the ground state. The stabilization energies are calculated to be in the range 2-5 kcal/mole for benzene-borazine and 5-18 kcal/mole for borazine-borazine, with interplanar separations near 3 A. in both cases.

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Electronic Structure of Cage Amines: Absorption Spectra of Triethylenediamine and Quinuclidine

Cited by 64 publications

References 19 publications

The effects of symmetry and rigidity on non-adiabatic dynamics in tertiary amines: a time-resolved photoelectron velocity-map imaging study of the cage-amine ABCO

The effects of symmetry and rigidity on non-adiabatic dynamics in tertiary amines: a time-resolved photoelectron velocity-map imaging study of the cage-amine ABCO

Non-Born–Oppenheimer wavepacket dynamics in polyatomic molecules: vibrations at conical intersections in DABCO

π-Molecular complexes: A modified CNDO study of the benzene-borazine system

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