Non-quadratic-intensity dependence of two-photon absorption induced fluorescence of organic chromophores in solution

Wang, C. H.; Tai, Oliver Y.-H.; Wang, Yuxiao; Tsai, Tsung-Hsiu; Chang, Nein-Chen

doi:10.1063/1.1850466

Cited by 15 publications

(10 citation statements)

References 20 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…We now turn to the physical origin of the intensity dependence of the PL signal. At high intensities, the slope of 2 which turns to a slope of 1 can be understood as PL induced by 2PA, which begins to saturate at high intensities and has been observed before in other materials . At lower intensities, there is an asymptotic quartic (power exponent 4) dependence on laser intensity that is more surprising.…”

Section: Resultsmentioning

confidence: 58%

Photon Upconversion in Crystalline Rubrene: Resonant Enhancement by an Interband State

et al. 2018

View full text Add to dashboard Cite

Triplet–triplet exciton annihilation after sensitization of the triplet states by a near-infrared (NIR)-absorbing sensitizer enables rubrene to function as a photon upconversion (UC) material. In this paper, we demonstrate an alternate pathway to NIR upconversion in pristine rubrene crystals: resonantly enhanced two-photon absorption via a weakly allowed interband state. We find that all crystalline rubrene samples exhibit NIR-to-visible upconversion that can be easily observed by eye under low-intensity (20 W/cm2) continuous wave excitation. The amount of continuous wave photoluminescence (PL) is comparable to what is observed under femtosecond pulsed excitation with the same average intensity. A wide range of excitation intensities (I) for the PL power dependence are explored and careful fitting of the intensity dependence of the upconverted PL shows that it has an approximate I 4 → I 2 transition. Moreover, there is a pronounced dependence of the per-pulse upconverted PL signal on the laser repetition rate. A four-state kinetic model with a long-lived (∼1 μs) interband state that takes into account fission and fusion dynamics can reproduce both the I 4 → I 2 transition and the dependence of the PL on pulse repetition rate. The modeling suggests that this interband state arises from a low-concentration species, possibly a crystal defect or defective rubrene molecules. Several other polyacene crystals (tetracene, diphenylhexatriene, and perylene) measured under the same conditions did not exhibit similar behavior. The observation of resonantly enhanced upconverted PL without the addition of chemically distinct sensitizers suggests that interband states in organic molecular crystals can generate new and possibly useful photophysical behavior.

show abstract

Section: Resultsmentioning

confidence: 58%

Photon Upconversion in Crystalline Rubrene: Resonant Enhancement by an Interband State

et al. 2018

View full text Add to dashboard Cite

show abstract

“…TPIF intensity of an aqueous solution of R6G varies as the square of input intensity of incident femtosecond laser pulse at 780 nm wavelength. Quenching of fluorescence intensity at higher laser powers [39,40] was observed, which led to deviation from the square law behavior of TPIF intensity. Therefore, sufficiently lower laser power was used to study the effect of CTAB on TPIF from R6G dye.…”

Section: Two-photon Induced Fluorescence Studymentioning

confidence: 83%

Investigating Two-Photon-Induced Fluorescence in Rhodamine-6G in Presence of Cetyl-Trimethyl-Ammonium-Bromide

2016

View full text Add to dashboard Cite

We investigate the effect of cetyl-trimethyl-ammonium-bromides (CTAB) concentration on the fluorescence of Rhodamine-6G in water. This spectroscopic study of Rhodamine-6G in presence of CTAB was performed using two-photon-induced-fluorescence at 780 nm wavelength using high repetition rate femtosecond laser pulses. We report an increment of ∼10 % in the fluorescence in accordance with ∼12 % enhancement in the absorption intensity of the dye molecule around the critical micellar concentration. We discuss the possible mechanism for the enhancement in the two-photon fluorescence intensity and the importance of critical micellar concentration.

show abstract

“…At higher power values, saturation occurs. A nonquadratic dependence of TPF at higher excitation powers is expected as higher energy levels become increasingly occupied . The occupation of these higher energy levels is proportional to the two-photon absorption cross section, which is extremely high for bacteriorhodopsin .…”

Section: Resultsmentioning

confidence: 99%

Fluorescence-Free Spectral Dispersion of the Molecular First Hyperpolarizability of Bacteriorhodopsin

Coene¹,

Cleuvenbergen²,

Steerteghem³

et al. 2017

J. Phys. Chem. C

View full text Add to dashboard Cite

The molecular first hyperpolarizability (β) of bacteriorhodopsin was measured over a broad spectral range (800–1300 nm) by means of a spectral hyper-Rayleigh scattering setup. We observed that two-photon fluorescence introduced a systematic error toward overestimating the β value. Spectrally resolved hyper-Rayleigh scattering allowed us to quantify and correct for this effect, resulting in a drop to about one-half of the β value reported in the literature. Moreover, we determined the dispersion of β over the wavelength range between 800 and 1300 nm. Applications such as second harmonic generation (SHG) imaging rely on accurate molecular first hyperpolarizability values, along with information about resonance effects and wavelength-dependent photodamage. With new and more accurate measurement setups, it will be possible to gain more insight into the nonlinear optical response of bacteriorhodopsin.

show abstract

Non-quadratic-intensity dependence of two-photon absorption induced fluorescence of organic chromophores in solution

Cited by 15 publications

References 20 publications

Photon Upconversion in Crystalline Rubrene: Resonant Enhancement by an Interband State

Photon Upconversion in Crystalline Rubrene: Resonant Enhancement by an Interband State

Investigating Two-Photon-Induced Fluorescence in Rhodamine-6G in Presence of Cetyl-Trimethyl-Ammonium-Bromide

Fluorescence-Free Spectral Dispersion of the Molecular First Hyperpolarizability of Bacteriorhodopsin

Contact Info

Product

Resources

About