Two-photon Absorption Wavelength Research Articles

Direct Multiphoton Femtosecond Infrared Laser Excitation of a Diamond Lattice in the Two-Phonon Region and Modification of Color Centers

The nonlinear absorption of ultrashort laser pulses with intensities of 0.17–1.7 TW/cm2 at an intrinsic two-photon absorption wavelength of 4673 nm in type IIb diamond has been studied experimentally. It has been shown that the main absorption mechanism in the studied sample is two-photon absorption with a coefficient of β2 = (72 ± 7) cm/TW. Transmission microspectroscopy, visible photoluminescence, and infrared Fourier-transform microspectroscopy have demonstrated the possibility of laser-induced transformation of nitrogen impurity centers in synthetic type Ib diamond at higher radiation intensities.

Impact of Five-membered Heterocyclic Rings on Photophysical Properties Including Two-photon Absorption Character

Abstract A series of dipolar-type terphenyl derivatives 1–3 featuring an electron donor (p-NMe2C6H4 group) and acceptor (p-NO2C6H4 group) unit was synthesized and their photophysical properties were investigated. By using aromatic heterocycles (thiophene, furan, pyrrole) as the π-linkers between the donor and acceptor units, significant effects on the bathochromic shift and enhancement of the two-photon absorption wavelength and the two-photon absorption cross-sections were observed, respectively.

Two-Photon Absorption Activity of BOPHY Derivatives: Insights from Theory

We present a theoretical study of a two-photon absorption (2PA) process in dipolar and quadrupolar systems containing two BF2 units. For this purpose, we considered 13 systems studied by Ponce-Vargas et al. [J. Phys. Chem. B2017, 121, 10850−1085829136383] and performed linear and quadratic response theory calculations based on the RI-CC2 method to obtain the 2PA parameters. Furthermore, using the recently developed generalized few-state model, we provided an in-depth view of the changes in 2PA properties in the molecules considered. Our results clearly indicate that suitable electron-donating group substitution to the core BF2 units results in a large red-shift of the two-photon absorption wavelength, thereby entering into the desired biological window. Furthermore, the corresponding 2PA strength also increases significantly (up to 30-fold). This makes the substituted systems a potential candidate for biological imaging.

Responsive mechanism and coordination mode effect of a bipyridine-based two-photon fluorescent probe for zinc ion**Project supported by the Natural Science Foundation of Shandong Province, China (Grant No. ZR2014AM026).

The properties of one-photon absorption (OPA), emission and two-photon absorption (TPA) of a bipyridine-based zinc ion probe are investigated employing the density functional theory in combination with response functions. The responsive mechanism and coordination mode effect are explored. The structural fluctuation is illustrated by molecular dynamics simulation. The calculated OPA and emission wavelengths of the probe are consistent with the experimental data. It is found that the red-shift of OPA wavelength and the enhancement of TPA intensity are induced by the increased intra-molecular charge transfer mechanism upon metal binding. The structural fluctuation could result in the blue-shift of TPA wavelength and the decrease of the TPA cross section. The TPA properties are quite different among the zinc complexes with different coordination modes. The TPA wavelength of the complexes with two ligands is close to that of the probe, which is in agreement with the experimental observation.

Isomerism and coordination mode effects on two-photon absorption of tris(picolyl)amine-based fluorescent probes for zinc ions**Project supported by the Natural Science Foundation of Shandong Province, China (Grant No. ZR2014AM026) and the Taishan Scholar Project of Shandong Province, China.

One-photon absorption and two-photon absorption (TPA) properties of three tris(picolyl)amine-based zinc ion sensors are investigated by employing the density functional response theory in combination with the polarizable continuum model. The different isomer and coordination geometry of each probe are taken into account. Special emphasis is placed on the effects of isomerism and the coordination mode on the optical properties. The intra-molecular charge transfer (ICT) properties are specified by natural bond orbital charge analysis. It is shown that the isomerism has non-negligible effects on TPA properties of free ligands. It is found that both the TPA wavelength and the cross section are highly dependent on the coordination mode. When the zinc ion connects with the picolyl unit in the middle of a ligand, the zinc complex has a large TPA intensity in a long wavelength range due to the increased ICT mechanism.

Dispersion of nonresonant third-order nonlinearities in GeSiSn ternary alloys.

Silicon (Si), tin (Sn), and germanium (Ge) alloys have attracted research attention as direct band gap semiconductors with applications in electronics and optoelectronics. In particular, GeSn field effect transistors can exhibit very high performance in terms of power reduction and operating speed because of the high electron drift mobility, while the SiGeSn system can be constructed using CMOS-compatible techniques to realize lasers, LED, and photodetectors. The wide Si, Ge and Sn transparencies allow the use of binary and ternary alloys extended to mid-IR wavelengths, where nonlinearities can also be employed. However, neither theoretical or experimental predictions of nonlinear features in SiGeSn alloys are reported in the literature. For the first time, a rigorous and detailed physical investigation is presented to estimate the two photon absorption (TPA) coefficient and the Kerr refractive index for the SiGeSn alloy up to 12 μm. The TPA spectrum, the effective TPA wavelength cut-off, and the Kerr nonlinear refractive index have been determined as a function of alloy compositions. The promising results achieved can pave the way to the demonstration of on-chip nonlinear-based applications, including mid-IR spectrometer-on-a-chip, all-optical wavelength down/up-conversion, frequency comb generation, quantum-correlated photon-pair source generation and supercontinuum source creation, as well as Raman lasing.

Theoretical investigation on ratiometric two-photon fluorescent probe for Zn2+ detection based on ICT mechanism

OPA (one-photon absorption), TPA (two-photon absorption) and fluorescence properties of a free ligand L upon coordination with Zn2+, and the regeneration with CN− were investigated in theory. According to our research, OPA spectra of ligand L show red-shift binding with Zn2+ while blue-shift with CN−. The fluorescence spectra and TPA wavelength are shifted in the same situation as those of OPA spectra. The value of TPA cross-section decreased at first, and then increased to 1813 GM for [L-Zn(CN)4]2−. Intramolecular charge transfer (ICT) mechanism was investigated by natural bond orbital (NBO) analysis. It demonstrates that L is hopeful to be a good ratiometric fluorescent probe for zinc ion detection in solution, and it can regenerate after CN− was introduced.

1,4-二(4'- N , N -二苯胺基苯乙烯基)苯衍生物单双光子吸收性质的理论研究

With the development of two-photon microscopy, getting excellent two-photon fluorescence dyes become a hot topic. In this work, the equilibrium geometries, electronic structures, one- and two-photon absorption properties and the fluo- rescent emission properties for a series of D-π-A-π-D type 1,4-di(4'-N,N-diphenylaminostyryl)benzene (DPA-DSB) deriva- tives were investigated by the density functional theory (DFT). The results show that the one photon absorption wavelengths of this series of one-dimensional linear conjugated molecules are in the range 370~540 nm, fluorescence emission wave- lengths are in the range 435~700 nm, provided the absorption of the UV to green light and the emission of the all visible range. The Stokes shifts are in the 47~270 nm range. Thus, these molecules provide broad color fluorophore options mole- cules for biological fluorescence imaging and fluorescence microscopy. The response function approach has been used to calculate the two-photon properties. Analysis of two-photon properties of these molecules suggests that these molecules two-photon absorption wavelengths are at 650~880 nm. The molecules 2, 4, 5, 6, 8 and 12, 14 have two-photon absorption in the infrared light range, which means these molecules can be used as alternative molecules to design the infrared medical material. These molecules have the fluorescence signal in the visible range and excellent two-photon characteristics; can be used as two-photon fluorescent probes biomarkers and alternative materials. Analyzing its structure and optical properties indicate that the modification or replacement of the electron-withdrawing group in the center of the molecule can effectively shift its electronic spectrum, the addition of N atom or S atom can significantly improve the two-photon absorption cross-section. For the acetylenyl moiety as π bridge, if the molecular plane did not change compared with ethylene bridge, it makes the two-photon absorption cross-section decreases; if acetylene bridge improved the planarity of molecule, it causes two-photon absorption cross-section increases. This study aims to understand the relationship between molecular structure and two-photon properties and offer some important information for the design and synthesis of novel materials. Keywords DPA-DSB derivative; one-photon absorption; fluorescence emission; two-photon absorption; two-photon ab- sorption cross-section

Atomic orientation following predissociation of the C 3Πg Rydberg state of molecular oxygen

(2 + 1) resonance enhanced multiphoton ionization in combination with time-of-flight mass spectroscopy (TOF-MS) has been used to detect both the O((3)P) and O((1)D) fragments produced as a result of predissociation of the C (3)Πg (v = 0) and (v = 1) Rydberg states of O2, accessed via two-photon absorption from the ground X (3)Σg(-) state. In particular, TOF profiles have been recorded at various fixed two-photon absorption wavelengths within the two bands, with circular polarized probe laser light used to probe the angular momentum orientation of these photofragments. All photofragments are found to display coherent orientation resulting from interference between two possible two-photon absorption pathways. The measured orientation is affected by rotational depolarization due to the long lifetime of the excited C state; once this effect is accounted for the orientation is found to be nearly constant over all dissociation wavelengths. The origin of the coherent orientation is attributed to two-photon absorption to different spin-orbit components of the C state.

Two- and Three-Photon Absorption Induced Emission, Optical Limiting and Stabilization of CdTe/CdS/ZnS Quantum Tripods System

Two- and three-photon absorption and excitation properties of CdTe/CdS/ZnS quantum tripods in chloroform have been investigated by using ~160-fs laser pulses in the spectral range of ~(1150-1650) nm. The two- and three-photon excited up-conversion emission is located around 740-nm position; the emission intensity follows the square law and cubic law on the excitation intensity for the former and the latter, respectively. The nonlinear transmission and output/input characteristics have been measured at a two-photon absorption wavelength of 1175 nm and a three-photon absorption wavelength of 1580 nm separately. Fairly good optical power limiting and stabilization performance of this material have been achieved.

Theoretical Investigation on the One‐ and Two‐photon Absorption Properties of Porphyrin‐thiophene Chromophores

AbstractTwo series of porphyrin‐thiophene chromophores were theoretically studied that exhibit large two‐photon absorption cross‐section in the visible region. The density functional theory (DFT) associated with ZINDO/SDCI methods has been used to calculate the molecular geometries, electronic structures, one‐photon and two‐photon absorption properties. The results show that the number of thiophene units affects the properties of one‐photon absorption (OPA) and two‐photon absorption (TPA). Porphyrin‐thiophene chromophores featuring two or three thiophene units have wide TPA response ranges; they can be applied to many nonlinear optical areas, such as optical limiting. Intervening ethynyl unit is beneficial to extend the conjugated pathway, and increase the two‐photon absorption cross‐section. At the same time, the OPA and TPA wavelengths are bathochromically shifted. From viewpoint of the high transparency and large nonlinear optical response, porphyrin‐thiophene chromophores will be promising TPA materials.

Two-Photon Absorption Cross-Sections from Electronic Structure Methods: Mesoionic Compounds

Absorption of two photons by organic molecules has many important technological applications, making theoretical modeling and synthesis of new molecules with large values of cross-sections, δ(ω), much needed activities. In this article, we present a computational procedure based on semiempirical electronic structure methods, which allows us to rank a series of homologous compounds in terms of δ(ω), as well as estimate single- and two-photon absorption wavelengths. This procedure uses a truncated version of the expression for the two-photon absorption peak, which retains only 4 of the 24 terms of the nontruncated equation and results in two-photon absorption peaks that are nearly identical to the ones obtained using all 24 terms, provided the incident photon energy is far from one-photon resonances. When the incident photon energy gets closer to one-photon resonances, the negative component of the hyperpolarizability becomes dominant and we advance a simplified, but still exact, form of this negative compo...

Synthesis and Structure-Linear and Structure-Nonlinear Optical Properties of Multi-Dipolar Zigzag Oligoaryleneethynylenes

A novel series of monodisperse, multi-dipolar zigzag oligoaryleneethynylenes DA(n) and D-Ar-A(n), bearing electron-donating dibenzothiophene and electron-accepting dibenzothiophene dioxide as arenes, with up to six charge-transfer (dipolar) units have been designed and synthesized by palladium-catalyzed Sonogashira coupling reactions. The linear and nonlinear optical properties of these multi-dipolar oligoaryleneethynylenes can easily be modified or enhanced by incorporating/extending with various central aryleneethynyl moieties such as phenylethynyl, oligo(9,9-dibutylfluorenyl)ethynyl, and oligothienylethynyl within the donor-acceptor units. Interestingly, the absorption and emission of these zigzag oligoaryleneethynylenes are not dependent on the number of covalently linked dipolar chromophores; however, the fluorescence quantum efficiencies consistently decrease with increased number of covalently linked dipolar units. These zigzag oligoaryleneethynylenes exhibit a linear increase in the two-photon absorption (TPA) cross-sections with increased number of covalently linked dipolar units without red-shifting the absorption and emission spectra. In addition, very large TPA cross-sections in the femtosecond regime (sigma(800) = 1306 GM in DMF or sigma(750) = 1522 GM in CH(2)Cl(2)) were obtained for D-TF-A(4) despite the moderate strength of the donor-acceptor pair. Our results suggest that the TPA properties of these zigzag oligoaryleneethynylenes including TPA wavelength and TPA cross-section can easily be tuned by means of modifying the central aryleneethynylene units and increasing the number of dipolar units, respectively. This approach provides an alternative means to tune or enhance the TPA cross-section at a specific wavelength.

Theoretical Study of One- and Two-Photon Absorption Properties of Octupolar D2d and D3 Bipyridyl Metal Complexes

The molecular equilibrium structures, electronic structures, and one- and two-photon absorption (TPA) properties of C2v (Zn(II), Fe(II) and Cu(I)) dipolar and D2d (Zn(II) and Cu(I)) and D3 (Zn(II)) octupolar metal complexes featuring different functionalized bipyridyl ligands have been studied by the ZINDO-SOS method. The calculated results show that one- and two-photon absorption properties of metal complexes are strongly influenced by the nature of the ligands (donor end groups and pi linkers) and metal ions as well as by the symmetry of the complexes. The length of the pi-conjugated backbone, the Lewis acidity of the metal ions, and the increase of ligand-to-metal ratio result in a substantial enhancement of the TPA cross sections of metal complexes. Substitution of C=N and N=N for C=C plays an important role in altering the maximum TPA wavelengths and the maximum TPA cross sections of metal complexes. Of them, the C=N substituted metal complexes have relatively large TPA cross sections. Replacing styryl with thienylvinyl makes the one-photon absorption wavelength red shift and at the same time leads to a great decrease of the maximum TPA cross sections of metal complexes. The possible reason is discussed. In the range 500-1250 nm, octupolar metal complexes exhibit intense TPAs and therefore are promising candidates for TPA materials.

Resonance enhancement of optical second harmonic generation in a ZnO nanowire

Two-photon absorption measurement has been carried out in a single 80nm×10μm ZnO nanowire using femtosecond laser pulses in the wavelength range of 700–800nm. In addition to the deep-level green emission around 530nm due to surface defects and the near band-edge ultraviolet emission around 360nm due to the exciton, a second harmonic peak has been observed. The strength of the frequency-doubled component is found to enhance while the two-photon absorption wavelength is tuned towards the exciton wavelength of the nanowire. This behavior can be ascribed to the resonant exciton absorption in ZnO nanowires.

Theoretical investigation on the two-photon absorption of C 60

We present a theoretical study on the two-photon absorption (TPA) properties of C 60. On the basis of the equilibrium geometry optimized by B3LYP/6-31G method, we employ the ZINDO method combined SOS formula to investigate the second hyperpolarizability and TPA cross section of C 60. The calculated result of the real part of the second hyperpolarizability of C 60 is in good agreement with the previous calculation and the experimental observation. In the 400–1000 nm range of TPA wavelength, we calculated TPA cross sections corresponding to all two photon allowed states. As a result, we find that there is only a TPA cross section maximum—995.7×10 −50 cm 4 s/photon at 518 nm. Another interesting phenomenon is that C 60 possesses the distinct TPA process in contrast to other conjugated molecules in terms of three-state approximation. This paper provides a theoretical basis of further studying TPA properties of C 60.

Upconversion fluorescence and optical power limiting effects based on the two- and three-photon absorption process of a new organic dye BPAS.

A new organic dye, trans-4, 4'-bis(pyrrolidingl) stilbene (BPAS), with large two-photon absorption (TPA) and three-photon absorption (3PA) has been synthesized. The molecular TPA cross section sigma2' at 550-670 nm and the 3PA cross section sigma3' at 720-1000 nm have been measured. The biggest sigma2' and sigma3' was 5.77 x 10(-47) cm4s/photon and 27 x 10(-75) cm6 s2 at 600 and 980 nm, respectively. In the experiment process we found that the strongest TPA wavelength is not at two times of the strongest linear absorption wavelength, but there is some blue shift. The 3PA-induced optical power-limiting properties have also been illustrated at 980 nm.

Nonlinear absorption and upconversion properties of two-photon absorption dye: ASPI

Two-photon absorption (TPA) cross sections of an organic dye, trans-4-[ p-( N-hydroxyethyl- N-methylamino)tyryl]- N-methylpyridinium iodide (abbreviated as ASPI), from 720 to 1100 nm have been measured by using nonlinear transmittance method, which reflect the TPA degrees of the dye at different wavelengths. The maximum TPA wavelength is located at 930 nm . The upconversion efficiencies of ASPI in dimethyl formamide and benzyl alcohol at different pump wavelengths have also been measured. There is 90 nm red shift for the highest upconversion wavelength as comparing with the strongest TPA wavelength. The influences of the solvents on the TPA-induced emission spectrum and the conversion efficiencies have also been given.