“…Thus, the shielding may prevent aggregation of the dyes and thereby increase the NLO absorption of the chromophore. As mentioned in the Introduction, it has been shown that both TPA and ESA contribute to OPL for Pt(II)-acetylides. ,,,− 2 OPL for Pt-ethynyl, Acetonide-G1-Pt, and Acetonide-G3-Pt, in THF (30 mM) at 532 nm.…”
Section: Resultsmentioning
confidence: 96%
“…Pt acetylides have proven to be NLO compounds that could have potential use as OPL materials. − The incorporation of the platinum nuclei into the structure promotes delocalization of π-electrons as well as intersystem crossing between the singlet and triplet states due to spin−orbit coupling. It has been shown that the Pt−ethynyl compound bis((4-(phenylethynyl)phenyl)ethynyl)bis(tributylphosphine)platinum(II) shows OPL by ESA from the triplet states over a wide part of the visible spectrum and also TPA at longer wavelengths. − Here we present results of the successful synthesis of dendrons attached to such OPL moieties and moreover investigate how the dendritic substituents affect the OPL properties of this organometallic chromophore. The dendrons (generation one to four) were grown by means of divergent synthesis utilizing the versatile chemistry of the acetonide protected bis-MPA anhydride. − …”
The effect of dendritic substituents on a nonlinear optical chromophore for optical power limiting (OPL) has been investigated. Synthesis and characterization of bis((4-(phenylethynyl)phenyl)ethynyl)bis-(tributylphosphine)platinum(II) with dendritic end groups are described. Polyester dendrimers up to the fourth generation were grown divergently using the anhydride of 2,2-bis(methylol)propionic acid (bis-MPA). The introduction of the dendritic moieties onto the NLO chromophore enables further processing of the materials using polymeric and related techniques. OPL measurements performed at 532, 580, and 630 nm show that the OPL properties improve with increasing size of the dendritic substituent. It is also shown that the addition of the dendrons increase the OPL as compared to the nondecorated bis((4-(phenylethynyl)phenyl)ethynyl)bis-(tributylphosphine)platinum(II). By use of femtosecond z-scan measurements carried out at different pulse-repetition frequencies, it is shown that the two-photon absorption cross section is ∼10 GM. Using pulse repetition frequencies (100 kHz-4.75 MHz) so that the time between the pulses is comparable with the triplet excited lifetime, the z-scans become dominated by excited-state absorption of excited triplet states.
“…Thus, the shielding may prevent aggregation of the dyes and thereby increase the NLO absorption of the chromophore. As mentioned in the Introduction, it has been shown that both TPA and ESA contribute to OPL for Pt(II)-acetylides. ,,,− 2 OPL for Pt-ethynyl, Acetonide-G1-Pt, and Acetonide-G3-Pt, in THF (30 mM) at 532 nm.…”
Section: Resultsmentioning
confidence: 96%
“…Pt acetylides have proven to be NLO compounds that could have potential use as OPL materials. − The incorporation of the platinum nuclei into the structure promotes delocalization of π-electrons as well as intersystem crossing between the singlet and triplet states due to spin−orbit coupling. It has been shown that the Pt−ethynyl compound bis((4-(phenylethynyl)phenyl)ethynyl)bis(tributylphosphine)platinum(II) shows OPL by ESA from the triplet states over a wide part of the visible spectrum and also TPA at longer wavelengths. − Here we present results of the successful synthesis of dendrons attached to such OPL moieties and moreover investigate how the dendritic substituents affect the OPL properties of this organometallic chromophore. The dendrons (generation one to four) were grown by means of divergent synthesis utilizing the versatile chemistry of the acetonide protected bis-MPA anhydride. − …”
The effect of dendritic substituents on a nonlinear optical chromophore for optical power limiting (OPL) has been investigated. Synthesis and characterization of bis((4-(phenylethynyl)phenyl)ethynyl)bis-(tributylphosphine)platinum(II) with dendritic end groups are described. Polyester dendrimers up to the fourth generation were grown divergently using the anhydride of 2,2-bis(methylol)propionic acid (bis-MPA). The introduction of the dendritic moieties onto the NLO chromophore enables further processing of the materials using polymeric and related techniques. OPL measurements performed at 532, 580, and 630 nm show that the OPL properties improve with increasing size of the dendritic substituent. It is also shown that the addition of the dendrons increase the OPL as compared to the nondecorated bis((4-(phenylethynyl)phenyl)ethynyl)bis-(tributylphosphine)platinum(II). By use of femtosecond z-scan measurements carried out at different pulse-repetition frequencies, it is shown that the two-photon absorption cross section is ∼10 GM. Using pulse repetition frequencies (100 kHz-4.75 MHz) so that the time between the pulses is comparable with the triplet excited lifetime, the z-scans become dominated by excited-state absorption of excited triplet states.
“…A Gaussian beam profile was obtained by spatial filtering the excitation beam before the Z-scan setup. For nonlinear measurements, the samples were prepared in a concentration of 10 18 molecules/cm 3 (1.7 × 10 3 Mol/L) and placed in a 2 mm fused silica cell. For absorptive nonlinearities, the light field induces an intensity dependent absorption and α = α 0 + βI + γI 2 + …, where I is the laser beam intensity, α 0 is the linear absorption coefficient, β and γ are the 2PA and 3PA coefficients, respectively.…”
Section: B Optical Measurementsmentioning
confidence: 99%
“…Furthermore, organometallics usually present intersystem crossing to a triplet state, which can be assisted by 2PA [9]. In the class of organometallic compounds, platinum acetylide complexes have been attracting special attention as interesting candidates for applications [10,11]. These compounds present high conjugation length and a center with weak bound electrons, which may result in relatively high multi-photon cross-section [12,13].…”
Abstract: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 crosssection spectra were interpreted using the sum-over-essential-states approach, considering a three-energy-level diagram.
“…3 It is difficult to keep particles in suspensions from agglomerating or to precipitate; 3 also, molecules in solution have had breakdown products fouling cuvette surfaces at high fluences. 50 For practical laser protection devices, these problems are best solved using solid-state materials. The requirement on thick bulk samples increases the impact of linear absorption.…”
Abstract. Reverse saturable absorbers have shown great potential to attenuate laser radiation. Good candidate molecules and various particles have successfully been incorporated into different glass matrices, enabling the creation of self-activated filters against damaging laser radiation. Although the performance of such filters has been impressive, work is still ongoing to improve the performance in a wider range of wavelengths and pulse widths. The purpose of this tutorial is, from an optical engineering perspective, to give an understanding of the strengths and weaknesses of this class of smart materials, how relevant photophysical parameters are measured and influence system performance and comment on the pitfalls in experimental evaluation of materials. A numerical population model in combination with simple physical formulas is used to demonstrate system behavior from a performance standpoint. Geometrical reasoning shows the advantage of reverse saturable absorption over nonlinear scattering due to a fraction of scattered light being recollected by imaging system optics. The numerical population model illustrates the importance of the optical power limiting performance during the leading edge of a nanosecond pulse, which is most strongly influenced by changes in the two-photon absorption cross section and the triplet linear absorption cross section for a modeled Pt-acetylide. This tutorial not only targets optical engineers evaluating reverse saturable absorbing materials but also aims to assist researchers with a chemistry background working on optical power limiting materials. We also present photophysical data for a series of coumarins that can be useful for the determination of quantum yields and two-photon cross sections and show examples of characterization of molecules with excited triplet states.
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