Two-Photon Absorption Spectrum of a Single Crystal Cyanine-like Dye

Abstract

The two-photon absorption (2PA) spectrum of an organic single crystal is reported. The crystal is grown by self-nucleation of a subsaturated hot solution of acetonitrile, and is composed of an asymmetrical donor-π-acceptor cyanine-like dye molecule. To our knowledge, this is the first report of the 2PA spectrum of single crystals made from a cyanine-like dye. The linear and nonlinear properties of the single crystalline material are investigated and compared with the molecular properties of a toluene solution of its monomeric form. The maximum polarization-dependent 2PA coefficient of the single crystal is 52 ± 9 cm/GW, which is more than twice as large as that for the inorganic semiconductor CdTe with a similar absorption edge. The optical properties, linear and nonlinear, are strongly dependent upon incident polarization due to anisotropic molecular packing. X-ray diffraction analysis shows π-stacking dimers formation in the crystal, similar to H-aggregates. Quantum chemical calculations demonstrate that this dimerization leads to the splitting of the energy bands and the appearance of new red-shifted 2PA bands when compared to the solution of monomers. This trend is opposite to the blue shift in the linear absorption spectra upon H-aggregation.

Absorption Band Shapes of a Push–Pull Dye Approaching the Cyanine Limit: A Challenging Case for First Principle Calculations

“…molecules with a π-conjugated backbone exhibiting vanishing bond length alternation (BLA), 1 have found applications in several technological fields, such as dye-sensitized and bulk-heterojunction solar cells, [2][3][4][5] optical storage media, 6,7 and nonlinear optics. [8][9][10][11] Highly reliable computational methods are therefore needed for a deeper understanding of their electronic structures and for the rational design of new ones, which should logically include the estimation of the rates of the photochemical processes which occur in devices. 12 However, the easily polarizable electronic clouds of those compounds make them problematic and challenging systems for most of the computational approaches for large size molecules.…”

Saturable absorption and two-photon absorption of 1,2,5-thiadiazolo[3,4-g]quinoxaline based derivatives with near-infrared fluorescence

“…However, there are only relatively few classes of NIR dyes that are readily available. These include the phthalocyanines, cyanine dyes and squaraine dyes [7][8][9].…”

Experimental and theoretical studies of the second- and third-order NLO properties of a semi-organic compound: 6-Aminoquinolinium iodide monohydrate

“…For the macroscopic properties we use two different local field corrections: the anisotropic LorenzLorentz spherical cavity local field factors and the local field factors deduced by Wortmann and Bishop (W-B) [18] from an extension of the Onsager's reaction field model [19]. However, it must be pointed out that the intermolecular interactions in crystals, overlooked by the gas oriented model, may have an enhancing or diminishing effect on hyperpolarizability [20,21], so as an alternative to the calculations with the local field corrections, we have also calculated the molecular hyperpolarizabilities using ElectroStatic Potential (ESP) charges to describe the medium around the asymmetric unit. Very recently, it was developed one method, the finite field Berry phase approach [22], that makes the approximations underlying the oriented gas model unnecessary and allows one to predict nonlinear susceptibilities directly.…”