MIM method

The most commonly used semiempirical for describing PES s is the diatomics-in-molecules (DIM) method. This method uses a Hamiltonian with parameters for describing atomic and diatomic fragments within a molecule. The functional form, which is covered in detail by Tully, allows it to be parameterized from either ah initio calculations or spectroscopic results. The parameters must be fitted carefully in order for the method to give a reasonable description of the entire PES. Most cases where DIM yielded completely unreasonable results can be attributed to a poor fitting of parameters. Other semiempirical methods for describing the PES, which are discussed in the reviews below, are LEPS, hyperbolic map functions, the method of Agmon and Levine, and the mole-cules-in-molecules (MIM) method. 

If a molecule consists of several weakly coupled chromophores it may be advantageous to speak of intramolecular CT transitions. The MIM method for calculating the absorption spectra of complex molecules, which has been mentioned in the discussion of substituent effects in Section 2.4.2, is based on this idea. 

Figure lb. (middle) Relationship between the models of PPP and MIM methods... 

Analyses of the Electronic Transitions of Poly(vinyl cinnamate). The concerted cycloaddltlon of clnnamoyloxy group is essentially the reaction of the central double bond. Therefore, we can expect to obtain the clearer image than that hitherto considered in the photochemical reaction if the contributions of the central double bond for the excited states are calculated quantitatively. It is known that the state functions of PPP model can be rewritten to the linear combinations of LE and CT(charge transfer) functions of MIM method(7 ) when we use the same atomic orbitals as the base functions(i ). Using the technique, the state functions in Table 2 are rewritten and the results are collected in Table 3- The relationship between these two methods is illustrated in Fig.1 (b),(c). 

The state function of S2 becomes a complicated one in the MIM calculations(Table 3), in contrast with the single function VS-t i the PPP method. On the other hand, the state function of S- is expressed by a simple B2u function in the MIM method although it becomes very complicated in the PPP method. These features reflect the characteristic of the model adopted in each of the two methods MO is constructed by all the AO of the molecule in the PPP method and by the AO of each chromophore in the MIM method.(see Fig.l) From these discussion we can realize that S2 is a excited state spread all over the molecule( also see MO 6 and 7 in Table 2), and S- is a excited state localized in benzene ring and also realize the importance of the selection of the theoretical model in the comprehensive understanding of the experimental phenomena. 

MIM method Table 3), the contribution of the LE of ethylene extremely increases in T- compared with that in S2. The fact suggests that T-) is highly photosensitive on the basis of the concerted cycloaddition following the Woodward-Hoffmann s rule. 

The MIMS method has been used to analyze VOCs in environmental water and air samples as well as in the monitoring of chemical and biochemical processes.MIMS is faster than GC-FID and GC-ELCD. In comparison, the MIMS method in single ion mode was the more sensitive and the linear dynamic ranges were similar to those of the GC-FID method, although not all compounds could be separated because of the similarity of their mass spectra. ... 

Mims ENDOR involves observation of the stimulated echo intensity as a function of the frequency of an RF 7T-pulse applied between the second and third MW pulse. In contrast to the Davies ENDOR experiment, the Mims-ENDOR sequence does not require selective MW pulses. For a detailed description of the polarization transfer in a Mims-type experiment the reader is referred to the literature [43]. Just as with three-pulse ESEEM, blind spots can occur in ENDOR spectra measured using Mims method. To avoid the possibility of missing lines it is therefore essential to repeat the experiment with different values of the pulse spacing t. Detection of the echo intensity as a function of the RF frequency and t yields a real two-dimensional experiment. An FT of the x-domain will yield cross-peaks in the 2D-FT-ENDOR spectrum which correlate different ENDOR transitions belonging to the same nucleus. One advantage of Mims ENDOR over Davies ENDOR is its larger echo intensity because more spins due to the nonselective excitation are involved in the formation of the echo. 

Fig. 3 Comparison of the activity and reusability data for the direct synthesis of hydrogen peroxide using a 0.5% Au-0.5% Pd/TiOa catalyst synthesized by different strategies. Structural information of the catalyst is also provided. Key CIm conventional impregnation method Sim sol-immobilisation method MIm modified impregnation method Calc the dried catalysts are heated at 400 °C for 4 h under a static air atmosphere Red the dried catalysts are heated at 400 °C for 4 h under a flow of 5% H2 in He. SDCV size dependent compositional variation. The first "Gold rich" catalyst was prepared by the MIm method using a 2M HCl solution and the second "Gold rich" catalyst was prepared by the MIm method using a 2M NaCl solution and the last catalyst was prepared by the MIm method using a IM H2SO4 solution.

Supported monometallic noble metal catalysts (Ru, Pd and Pt) are reported to be effective for this reaction." Recently two supported nanoalloy systems (Au-Pd Ru-Pd supported on Ti02) showed very interesting catalytic behavior. Supported monometallic Au and Pd catalysts (1% Au/Ti02 1% Pd/Ti02) were not active for this reaction, however when were combined at a nanoscale, the catalyst (1% AuPd/Ti02) was extremely active for this reaction (Fig. 6a). This 1% AuPd/Ti02 nanoalloy catalyst was prepared via the MIm method mentioned in Example 1 of this chapter. Detailed spectroscopic and microscopic characterization of this catalyst revealed that Au and Pd are in a homogeneous random alloy... 

Although electronic transition energies are mainly obtained by semi-empirical SCF methods with limited configuration interaction (LCI) based on delocalized orbitals, the use of localized orbitals has some advantages for the interpretation of data. The latter procedure is known as the Molecules-in-Molecule (MIM) method. An extension of this method to ir-electron systems with heteroatoms has been given and exemplified for sulphur-containing compounds. Differences in the calculated spectral data between the PPP and MIM methods are small where the participating localized tt systems are weakly coupled. ... 

Thiochromanone (9) may be considered a derivative of thiophenol. The spectral excitation energies of (9) have been calculated satisfactorily by the MIM method and interpreted in terms of local excitations on benzene, and the charge-transfer transitions S - benzene, benzene CO, and S CO. ... 

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