Spectroscopic characterization of aggregation behavior in hemicyanine dye monolayer and multilayer systems

Song, Qin‐Hua; Evans, Christine; Bohn, Paul W.

doi:10.1021/j100153a050

Cited by 40 publications

(57 citation statements)

References 10 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…In general the SHG field is, for fixed input energy and geometry, proportional to the surface nonlinear susceptibility, (2) S . This is in turn related to the molecular hyperpolarizability, R (2) , coverage, N A , and adsorbate orientation by 4 where ijk (2) is an element of the macroscopic surface nonlinear susceptibility. The prime indicates molecular frame, and 〈T〉 is the transformation matrix between molecular and laboratory frame.…”

Section: Resultsmentioning

confidence: 99%

“…Such measurements must be made on the dyes in the adsorbed state, as adsorption is frequently accompanied by aggregate formation which alters both the electronic spectra and nonlinear optical properties of the films. 2 In addition it has recently been shown that some adsorbed dyes exhibit persistent spectral holeburning at elevated temperatures. 3 Thus, such systems have considerable potential in the search for new optical data storage media.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Picosecond Dynamics of Adsorbed Dyes: A Time-Resolved Surface Second-Harmonic Generation Study of Rhodamine 110 on Silica

and

Meech

1996

J. Phys. Chem.

View full text Add to dashboard Cite

The picosecond dynamics of adsorbed rhodamine 110 have been observed by time-resolved surface second harmonic generation (SHG). This technique reveals details of the coverage-dependent photophysics and photochemistry of adsorbed dyes which are not available from, for example, fluorescence decay experiments. In particular the ground-state recovery was found to be biphasic, with recovery times of a few picoseconds and tens of microseconds. This behavior is attributed to an ultrafast internal conversion of the initially excited state followed by either fast vibrational relaxation to the initial ground state or a disruption of the dye layer in the hot ground state leading to a metastable form of the ground state with a reduced hyperpolarizability. Other models are discussed, but none readily reproduce the time-resolved SHG data. The large difference between solution phase and adsorbate photophysics is attributed to the formation on the surface of dimers and higher aggregates. The existence of such aggregates is revealed in the absorption spectra. Stationarystate SHG measurements show that the most probable adsorption geometry is with the molecular plane of the dye perpendicular to the surface; this is consistent with the formation of cofacial aggregates. With polarizationresolved SHG it was shown that the adsorbate orientation is not coverage dependent, at least between 0.2 and 1 monolayer; however, a meaningful angle of adsorption could not be determined.

show abstract

Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Picosecond Dynamics of Adsorbed Dyes: A Time-Resolved Surface Second-Harmonic Generation Study of Rhodamine 110 on Silica

and

Meech

1996

J. Phys. Chem.

View full text Add to dashboard Cite

show abstract

“…50,51 As the surface pressure increases, some phenomena take place in the reflection band: (1) ∆R norm at 475 and 265 nm decreases, which should be related to the decreasing of the polar tilt angle of the chromophores and (2) for π > 5 mN/m, the maximum wavelength of the lowenergy band shifts to shorter wavelengths (from 475 to 459 nm), this fact must be attributed to the formation of H aggregates of the SP chromophores.…”

Section: Methodsmentioning

confidence: 99%

Control of the Lateral Organization in Langmuir Monolayers via Molecular Aggregation of Dyes

et al. 2010

View full text Add to dashboard Cite

This paper shows that it is possible to construct well-defined 2D structures at the air-water interface in which the lateral organization is controlled by means of the preparation of mixed films, and selecting the components so that there are attractive interactions between them. The goal here is to establish the lateral connection between components through self-aggregation of the dye. This can be achieved by selecting a suitable balance between the sizes of the hydrophobic and polar groups. In such a way, the domain structure depends on the ability of the tilt dye to fill the available area. Thus, the molecular organization and the domain morphology of mixed films containing dimyristoyl-phosphatidic acid (DMPA) and the hemicyanine dye, 4-[4-(dimethylamino)styryl]-1-docosylpyridinium bromide (SP), have been studied by using Grazing Incidence X-ray Diffraction (GIXD), Brewster angle microscopy (BAM), and reflection spectroscopy at the air-water interface. For this mixed system, the formation of circular domains with bright horizontal regions and dark vertical regions was observed. Furthermore, depending on the temperature, it is observed as branches grow from circular domains, whose brightness depends on the growth direction. Thus, BAM images allow us to observe some branches that, as their growth direction changes, their brightness also changes simultaneously. The GIXD experiment permits us to relate the circular domains with an orthorhombic phase and the branches grown from the circles with an Overbeck phase. In both cases, the formed structures are induced by the hemicyanine aggregation. Circular BAM domain textures have been simulated by using the Fresnel equations for biaxial anisotropic materials.

show abstract

“…UV/vis absorbance spectra of aqueous solutions give no indication of aggregate formation as frequently reported for such dyes (25)(26)(27). The absorbance maxima are listed in Table 2.…”

Section: Evaluation Of Equilibrium Surface Tension Vs Concentration Imentioning

confidence: 59%

On the Adsorption Behavior of Soluble, Surface-Chemically Pure Hemicyanine Dyes at the Air/Water Interface

Lunkenheimer

Laschewsky

Warszyński

et al. 2002

Journal of Colloid and Interface Science

View full text Add to dashboard Cite

Spectroscopic characterization of aggregation behavior in hemicyanine dye monolayer and multilayer systems

Cited by 40 publications

References 10 publications

Picosecond Dynamics of Adsorbed Dyes: A Time-Resolved Surface Second-Harmonic Generation Study of Rhodamine 110 on Silica

Picosecond Dynamics of Adsorbed Dyes: A Time-Resolved Surface Second-Harmonic Generation Study of Rhodamine 110 on Silica

Control of the Lateral Organization in Langmuir Monolayers via Molecular Aggregation of Dyes

On the Adsorption Behavior of Soluble, Surface-Chemically Pure Hemicyanine Dyes at the Air/Water Interface

Contact Info

Product

Resources

About