Empirical treatment of solvent-solute interactions: medium effects on the electronic absorption spectrum of ?-carotene

Abstract

Solvent effects on the wavenumber of the maximum of the longest wavelength electronic absorption band of all-trans-b-carotene were determined in 34 solvents. Together with results from previous studies, a data set for 51 solvents, mostly non-hydrogen bond donors, was constructed. This information was analyzed in terms of reaction field models and also showed its value for correlation purposes when used either alone or in combination with standard empirical solvent polarity-polarizability scales.

Influence of Quadrupolar Molecular Transitions within Plasmonic Cavities

“…Vertical emission (along z -direction) from the (11) mode is captured in low-angle scattering spectra, while (10) and (20) preferentially out-couple at high angles (θ ∼ 60°, defined from the vertical direction), spectrally distinguished from the low-angle component . The experimental mode wavelengths agree with mode positions extracted from finite element method simulations performed with typical parameters for β-carotene nanogaps: D = 80 nm, w = 32 nm, n g = 1.56, and d = 2.4 nm (Figure d), where the facet width w has a linear dependence on the particle diameter ( w / D = 41%) and n g is defined by β-carotene molecules . Employing the plasmonic spectral resonances in NPoM as an effective plasmonic ruler, an average gap size of 2.4 ± 0.2 nm is estimated by comparing the simulated (10) mode position with the experimental dark-field distribution (Figure S1).…”

“… 23 The experimental mode wavelengths agree with mode positions extracted from finite element method simulations performed with typical parameters for β-carotene nanogaps: D = 80 nm, w = 32 nm, n g = 1.56, and d = 2.4 nm ( Figure 1 d), where the facet width w has a linear dependence on the particle diameter ( w / D = 41%) 35 and n g is defined by β-carotene molecules. 38 Employing the plasmonic spectral resonances in NPoM as an effective plasmonic ruler, an average gap size of 2.4 ± 0.2 nm is estimated by comparing the simulated (10) mode position with the experimental dark-field distribution ( Figure S1 ). 39 , 40 With these parameters, we achieve in our simulations a successful alignment of the spectral positions of all three optical modes ( Figure 1 c,d).…”

On the use of β‐carotene as a probe for solvent polarizability

“…Abe et al . also found that weakly acidic solvents such as dichloromethane, trichloromethane, 1,1‐dichloroethane, acetonitrile, nitromethane, diethylamine, aniline, and N ‐methylaniline depart only little from Eqn (one to two times of its sd at most).…”

“…Also, in 1998, Abe et al . found that the function f ( n ) = ( n 2 − 1)/( n 2 + 1) can be related to the absorption maxima of β‐carotene in nonpolar solvents by Eqn , from which they estimated the absorption maximum in the gas phase to be 0 = 24 678 cm −1 : with n = 17, r = 0.996, and sd = 31 cm −1 .…”

Anion Influence on Aggregation Behavior of Imidazolium-Based Ionic Liquid in Aqueous Solutions: Effect on Diverse Chemical Processes

“…This chemical probe is a polyene with a allowed π – π* polar transition along the longitudinal axis of the molecule . The π 2 * values were estimated by applying eq : , …”