Resolved vibronic spectrum

Vibronic spectra reflect changes in the electronic and vibrational state of a molecule at the same time. It is possible to calculate the geometry of the excited species and the potential hypersurface close to the equilibrium state. For this, a spectrum is required with sufficiently well resolved vibronic structure to carry... 

The chlorine atom is an electron-pulling substituent with a strong -I-effect overcoming a weak +M-effect therefore the electron density of the aromatic system is reduced. This results in a blue-shifted fluorescence compared to the parent p4P. The fact that the spectrum of CLP4 shows well-resolved vibronic structures indicates that the lone pairs of the chlorine atoms are not directly involved in the aromatic system that is, the fluorescence relevant transition has no charge transfer character. The blueshift is clearly due to an inductive effect, since the... 

Figure 5-1. Mass resolved excitation spectrum of bare aniline in a molecular jet. Several of the more intense vibronic transitions are assigned. 

The types of experiments mentioned above represent some of the important methods which can be tried in order to resolve vibronic structure in an electronic emission or absorption spectrum of a molecule or ion of interest. But what can we do when an interesting molecule cannot be studied by one of the above methods because of its properties (e.g., lack of solubility, volatility, photostability) What can we do when none of the experimental methods which are tried results in better resolution An obvious alternative is to turn to a different experimental technique. 

Mo2(02CCF3)4 [4]. The analysis of the distortions of this molecule is included here for two reasons. First, the spectra provide a detailed check on the use of the combination of electronic and Raman spectroscopy to determine distortions. The electronic spectrum contains more highly resolved vibronic bands than that in the previous example and thus provides a more detailed check of the distortions calculated from the pre-resonance Raman data. Second, the analysis is of chemical interest because the distortions are caused by a transition between orbitals forming the Mo—Mo... 

The vibronic spectra of Do — Di — D2 electronic states recoded by da Silva Filho et al. [45] revealed resolved vibrational structures of the Do and D2 electronic states and a broad and structureless band for the Di state. A slow ( 3-20 ps) and fast k, 200 fs) relaxation components are estimated for the Dq D2 transition in a (femto)picosecond transient grating spectroscopy measurements [16]. The fast component is attributed to the Do D2 transition and a nonradiative relaxation time of 212 fs is also estimated from the cavity ringdown (CRD) spectroscopy data [42]. Electronic structure results of Hall et al. [107] suggest that the nonradiative Do D2 relaxation occurs via two consecutive sloped type CIs [66,108]. We developed a global model PESs for the Do — Di— D2 electronic states and devised a vibronic coupling model to study the nuclear dynamics underlying the complex vibronic spectrum and ultrafast excited state decay of N +[20]. 

The low temperature and high-resolution absorption spectrum of permanganate as recorded by Holt and Ballhausen [12] is shown in Fig. 4. The first allowed band (I) starting at 2.27 eV (18,300 cm 1) has a well-resolved vibronic structure. It is followed by a featureless shoulder (II) at 3.47 eV (28,000 cm-1) and another strong band (III) at 3.99 eV (32,000 cm-1) with a clear vibronic fine structure. We finally have a strong featureless band (IV) at 5.45 eV (43,960 cm-1). 

Luminescence spectroscopy of single crystals is a technique that often leads to spectra with well-resolved vibronic structure. " In the vast majority of coordination compounds, luminescence is observed only from the lowest-energy excited state and often the polarizations are less distinct than in absorption spectra. An illustrative example is the spectrum of the square... 

Calculations of the ion yield in dependence on the pulse delay time At and on the parameters of the laser pulses have been performed in Refs. 86 and 93 for simple one-dimensional models of excited-state vibrational motion and vibronic coupling. It has been found that for the vibronic-coupling examples considered and for suitably chosen pulse parameters, the ion signal as a function of At maps very well the adiabatic electronic population probability. As an example of a molecular system comprising conical intersections. Sec. 5.1 presents a calculation of the time-resolved photoelectron spectrum of pyrazine. 

The first numerically exact simulation of a time-resolved photoelectron spectrum for a multidimensional vibronic-coupling system was reported... 

The fine and resolved vibronic structure of the pyrene emission spectrum coupled with the low water-solubility of this aromatic molecule, make pyrene a cheap, efficient, and polymer-cost effective fluorescent probe for characterizing micellar cores (eg, dielectric constants). 

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