Three-photon Absorption Spectra Research Articles

Arylphthalimidoporphyrins: New Approaches to Imaging pH and Temperature Simultaneously with Oxygen

Tetraarylphalimidoporphyrins (TAPIP) and diarylphalimidoporphyrins (DAPIP) possess unique photophysical properties that enable new and superior approaches to optical biological sensing of pH and temperature in parallel with oxygen. The syntheses of TAPIP and DAPIP have been reported by our group recently. We also have reported the photophysical properties of free-base (H2), Zn(II), Pt(II) and Pd(II) DAPIP and TAPIP, including their non-linear spectroscopic properties, such as two- and three-photon absorption spectra. Using a combination of phosphorescent Pt complexes of TAPIP and DAPIP we are designing a phosphorescent sensor for pH and oxygen, termed pHOx, which operates by measuring ratios of phosphorescence lifetimes. Unlike all existing optical pH sensors, measurements by pHOx are not affected by optical heterogeneities of the medium and provide unbiased pH readings in vivo simultaneously with pO2. At the same time, Pd complexes of TAPIP have been shown to emit both phosphorescence and thermally activated E-type delayed fluorescence, providing a functional element for optical sensing of temperature. However, to make the temperature readings unobstructed by optical heterogeneities of biological tissue, a PdTAPIP-based probe is supplemented by another probe system, based on H2DAPIP, which emits prompt fluorescence at the same wavelengths and can serve as a correction standard for unbiased temperature measurements.

Three-photon absorption spectra and bandgap scaling in direct-gap semiconductors

This paper presents three-photon absorption (3PA) measurement results for nine direct-gap semiconductors, including full 3PA spectra for ZnSe, ZnS, and GaAs. These results, along with our theory of 3PA using an eight-band Kane model (four bands with double spin degeneracy), help to explain the significant disagreements between experiments and theory in the literature to date. 3PA in the eight-band model exhibits quantum interference between the various possible pathways that is not observed in previous two-band theories. We present measurements of degenerate 3PA coefficients in InSb, GaAs, CdTe, CdSe, ZnTe, CdS, ZnSe, ZnO, and ZnS. We examine bandgap, E g , scaling using -band tunneling and perturbation theories that show agreement with the predicted E g − 7 dependence; however, for those semiconductors for which we measured full 3PA spectra, we observe significant discrepancies with both two-band theories. On the other hand, our eight-band model shows excellent agreement with the spectral data. We then use our eight-band theory to predict the 3PA spectra for 15 different semiconductors in their zinc-blende form. These results allow prediction and interpretation of the 3PA coefficients for various narrow to wide bandgap semiconductors.

Three-photon absorption spectra of zinc blende semiconductors: theory and experiment: erratum.

We provide a correction to the spectral dependence of the three-photon absorption in zinc-blende semiconductors using Kane's 4-band model in Opt. Lett.33, 2626 (2008).OPLEDP0146-959210.1364/OL.33.002626.

Three-photon-induced Luminescence of Europium Acetylacetonate-type Complexes

We measured the three-photon absorption spectra of two europium acetylacetonate-type complexes. The three-photon absorption peak wavelengths of tris(hexafluoroacetylacetonato)europium(III) (Eu(hfa)...

Optical nonlinearities and ultrafast all-optical switching of m-plane GaN in the near-infrared

We reported a systematic investigation on the three-photon absorption (3PA) spectra and wavelength dispersion of Kerr refraction of bulk m-plane GaN crystal with both polarization E⊥c and E//c by femtosecond Z-scan technique in the near-infrared region from 760 to 1030 nm. Both 3PA spectra and Kerr refraction dispersion were in good agreement with two-band models. The calculated nonlinear figure of merit and measured ultrafast nonlinear refraction dynamics via femtosecond pump-probe with phase object method revealed that m-plane GaN would be a promising candidate for ultrafast all-optical switching and autocorrelation applications at telecommunication wavelengths.

Characterization of two- and three-photon absorption of polyfluorene derivatives

Fluorene-based polymer derivatives are promising materials for organic electronic devices because of their photoluminescence and electroluminescence, good film-forming ability, and favorable chemical and thermal properties. Although optical properties of polyfluorene have already been reported, most of the studies focused on the linear optical properties, whereas nonlinear optical characteristics have only recently received more detailed attention. Here, we report on two polyfluorene derivatives, poly(9,9′-n-dihexyl-2,7-fluorenediyl) (LaPPS 10) and poly(9,9′-n-dihexyl-2,7-fluorene-diyl-vinylene) (LaPPS 38), which present intense nonlinear absorption and fluorescence. Two-photon absorption cross-section properties of both polymers were characterized in the spectral range from 500 nm up to 900 nm, reaching peak values around 2000 Goppert Mayer units. Optical limiting behavior and two-photon-induced fluorescence of both polymers have also been investigated. Furthermore, the first molecular hyperpolarizability of the polymers was also studied using hyper-Rayleigh scattering. In addition, the three-photon absorption (3PA) spectra of both materials were also investigated, and 3PA cross-section values in the order of 1 × 10−78 cm6 s2 photon−2 were observed. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2014, 52, 747–754

First principles studies on one-, two-, and three-photon absorption properties of a symmetric carbazole derivative both in gas phase and solution

One-, two-, and three-photon absorption spectra of a novel symmetric carbazole derivative have been calculated by applying density functional response theory, both in gas phase and in a selection of solvents with increasing polarity. The effect from surrounding solvents is described by the polarizable continuum model. The effect of the choice of geometry, as well as the exchange–correlation functional has been carefully analyzed. It is found that the Coulomb attenuation method variant of Becke’s three-parameter exchange and the Lee–Yang–Parr correlation functional (CAMB3LYP) can reproduce very well the experimental one-photon absorption lineshape. The dielectric solutions enhance both one- and multi-photon absorption properties. Possible explanations for the discrepancy between calculated and experimental three-photon absorption cross sections have been analyzed in details. The calculation suggests that the possible involvement of excite-state absorption in the experimental measurement cannot be ruled out.

Broadband three-photon absorption spectra of platinum acetylide complexes

We investigate the three-photon absorption spectra of four platinum acetylides complexes employing femtosecond pulses. We observed strong three-photon absorption cross-section in the near-infrared region (from 850 nm to 1200 nm). The three-photon absorption (3PA) spectra present resonance enhancement effect as two photons of the excitation wavelength approach the lower two-photon allowed states of the molecules as well as a 3PA allowed band around 1180 nm. The 3PA cross-section spectra were interpreted using the sum-over-essential-states approach, considering a three-energy-level diagram.

Steady-state analysis of three-photon absorption spectra via density-matrix method in a three-coupled-quantum-well nanostructure

We numerically simulate three-photon absorption spectra in a three-coupled-quantum-well nanostructure interacting with a pump field, a coherent coupling field, and a probe field. We find that the three-photon absorption spectra can be dramatically influenced due to the intensities of the coupling field and pump field changing under the three-photon resonance condition. The effect of the frequency detuning of the pump field on the three-photon absorption spectra is also discussed. The study in our case is much more practical than the study in the case of its atomic counterpart in the sense of flexible design and the wide adjustable parameters. Thus it may open up some new possibilities for technological applications in optoelectronics and solid-state quantum information science.

Three-photon absorption spectra of zinc blende semiconductors: theory and experiment

We calculate the spectrum of three-photon absorption (3PA) in zinc blende semiconductors using Kane's four-band model. We apply this to ZnSe and measure the 3PA spectrum using femtosecond pulses, obtaining excellent agreement. The spectrum shows the apparent onset of 3PA from the split-off band and also shows quantum interference between the several possible evolution pathways when exciting carriers from valence to conduction band.

Two- and Three-Photon Absorption and Frequency Upconverted Emission of Silicon Quantum Dots

In this communication, we present the experimental results of two- and three-photon excitation studies on silicon quantum dots (QDs) in chloroform (as well as in water) by using femtosecond laser pulses with wavelengths of 778 and 1,335 nm and a pulse duration approximately 160 fs. The photoluminescence spectral distributions are nearly the same upon one-, two-, and three-photon excitation. With one- and two-photon excitation, the temporal relaxation measurements of photoluminescence emission manifest the same multiexponential decay behavior in the time range from 0.05 ns to 15 micros, characterized by three successive decay constants: 0.75 ns, 300 ns, and 5 micros, respectively. Finally, the two-photon absorption spectrum in the spectral range of 650-900 nm and the three-photon absorption spectrum in the spectral range of 1,150-1,400 nm have been measured.

Three-photon absorption in ZnO and ZnS crystals

We report a systematic investigation of both three-photon absorption (3PA) spectra and wavelength dispersions of Kerr-type nonlinear refraction in wide-gap semiconductors. The Z-scan measurements are recorded for both ZnO and ZnS with femtosecond laser pulses. While the wavelength dispersions of the Kerr nonlinearity are in agreement with a two-band model, the wavelength dependences of the 3PA are found to be given by (3Ephoton/Eg-1)5/2(3Ephoton/Eg)-9. We also evaluate higher-order nonlinear optical effects including the fifth-order instantaneous nonlinear refraction associated with virtual three-photon transitions, and effectively seventh-order nonlinear processes induced by three-photon-excited free charge carriers. These higher-order nonlinear effects are insignificant with laser excitation irradiances up to 40 GW/cm2. Both pump-probe measurements and three-photon figures of merits demonstrate that ZnO and ZnS should be a promising candidate for optical switching applications at telecommunication wavelengths.

What to see and what not to see in three-photon absorption: (3+1) REMPI of HBr

Hönl–London type approximation expressions are derived for transition strengths of the Ω′=0,1,2,3, ←Ω″=0 (Σ, Π, Δ and Φ←Σ) three-photon transitions for diatomic molecules belonging to Hund’s case (a) and intermediate (a)–(b) coupling schemes. These are used to demonstrate what may be seen and what may not be seen in three-photon absorption spectra. The forms are used to simulate room temperature (3+1)REMPI spectra of HBr, for different electronic transitions. The analysis as well as comparison with (2+1)REMPI spectra is used to demonstrate the usefulness of three-photon absorption spectroscopy to identify excited states and to derive spectroscopic parameters. A Rydberg state, not observed in single or two-photon absorption, with band origin 82 837 cm−1 was identified and analyzed for the first time. It was assigned as the L1Φ(3) ((σ2π3)5dδ)) state, (0,0) band.

Three-photon-absorption spectroscopy in an indirect-gap material: CdI2.

The three-photon absorption (3PA) spectrum of an indirect-gap material (${\mathrm{CdI}}_{2}$) has been measured at 10 K by monitoring the resulting self-trapped-exciton emission. The contribution of excitonic transitions has been evidenced for excitation energies near the indirect gap, while the contribution of allowed and forbidden indirect transitions has been shown for excitation energies far from the gap. The spectral behavior of the 3PA coefficient has been described by parametric formulas, which are analogous to the ones successfully applied for 3PA in direct-gap materials.

Spectral behavior of three-photon absorption coefficient in II–VI compounds: ZnO, CdS and ZnSe

Three-photon absorption (3PA) spectra has been experimentally investigated in a large excitation energy range above the optical gap for three II–VI semiconductors (ZnO, CdS and ZnSe) with different band structures. The spectral behavior of 3PA coefficient has been demonstrated to be described by a parametric formula containing a varying number of different terms, whose energy dependence being predicted on the grounds of 3PA selection rules. A comparison between experimental and theoretical line-shapes has suggested that almost a linear k-dependence approximation for the optical matrix elements has to be always assumed in order to correctly describe the 3PA coefficient line shape.

Theoretical calculations on the three-photon absorption spectrum of benzene

The three-photon absorption spectrum of benzene is discussed by means of molecular orbital calculations of allowed and vibronic three-photon intensities to S 1 and S 2. The coupling mechanisms responsible for vibronic absorption to these states are described and it is found that vibronic pathways peculiar of the three-photon process may occur. Allowed intensities to S 1, S 2 and S 3 are in agreement with qualitative expectations from the alternant hydrocarbon theory. On the whole, the S 0 → S 1 three-photon calculations provide a good basis to discuss available experimental data.

The three-photon absorption spectrum of 127I 2 and 129I 2 in the region 16 500–18 500 cm −1

The multiphoton absorption of 127I 2 and 129I 2 has been examined under both low and high resolution, using either a single tunable dye laser or two independently tunable pump and probe dye lasers, operating in the green-red regions. The one-color spectrum excited by a single laser at low resolution shows “bands” that have been interpreted by previous workers as 2P1C excitation to one or more excited states in the 35 000 cm −1 region: but under high resolution, these bands reveal a complex rotational structure, which is reinterpreted as being due mainly to 3P1C transitions to the ion-pair states F′0 u +( 1D) and F0 u +( 3P 0) , for which molecular constants are derived. No evidence has been found from the spectral analysis for stable excited states of iodine at around 35 000 cm −1.

Three-photon absorption spectra in KI and RbI.

The three-photon absorption (3PA) spectra of KI and RbI have been measured at 80 K in a wide excitation-energy range by monitoring the resulting self-trapped exciton luminescence. The experimental results have shown that the spectral behavior of the 3PA coefficient is fully described by a parametric formula containing four different terms, their energy dependences being predicted on the grounds of 3PA selection rules. A qualitative and quantitative comparison between the experimental and the various theoretical 3PA line shapes has been carried out.

The three-photon absorption spectrum of the iodine molecule

The three-photon absorption spectrum of iodine has been recorded under high resolution, using both a single tunable dye laser (3P1C) and independently tunable pump and probe lasers (3P2C). Rotational analysis of the 3P2C spectrum confirms the presence of the F′(0 u +) state and gives improved spectroscopic constants. A separate set of vibrational levels in the 51500–54700 cm −1 energy region, with a spacing of 78 cm −1, has also been identified.

Vibronic intensities and rotational line strength factors for the three-photon absorption spectrum of ammonia

A perturbation theory approach is used to analyze the rovibronic structure of the three-photon resonant absorption of ammonia. The vibronic selection rules are presented in a convenient pyramid mnemonic in terms of irreducible representations of the rotation group and of the D3h point group. The analysis is presented for each possible situation, namely, all three photons are different, two photons are identical and one different, and all three photons are identical. The experimentally important case of three identical photons implies only two polarizations and two vibronic tensor elements for each symmetry type. With both the B̃ and C̃′ systems of ammonia one expects a ratio of 5 to 2 in the absorbance for circularly versus linearly polarized light for the N, O, S, and T branches. For the P, Q, and R branches one expects a 21 to 4 ratio of the weight-1 versus weight-3 tensor contributions to the C̃′ system in linearly polarized light (21 to 6 for B̃). Weight-1 terms are absent with circularly polarized light. These predictions are confirmed experimentally. The complete set of rotational line strength factors for three-photon absorption are given in algebraic form for the first time. The combination of vibronic factors, rotational line strengths, and statistical weights allows one to predict the three-photon absorption spectrum. Such calculated spectra are presented for ammonia at 45 K and they compare very favorably with the experimental spectra for both the B̃ system (a perpendicular band) and for the C̃′ system (a parallel band) in both linearly and circularly polarized light.