Shuyin Shen

Synthesis, spectroscopic and thermal properties of a series of azo metal chelate dyes

A series of azo metal chelate dyes have been synthesized. The UV-Vis absorption spectra of the azo dye and its metal complexes were measured. The stoichiometry of the complex was determined by the spectroscopic titration method to be 1:2 (ML2), and the formation constants of the complexes were evaluated. Thermal decomposition with a sharp exothermic peak was observed by TG-DT Analysis.

Optical recording performance of thin films of phthalocyanine compounds

Abstract As organic dyes with excellent thermal and light stability, phthalocyanine compounds have been investigated as write-once read-many optical recording materials. By selecting different substituents and metallic ions, the absorption bands of thin film of phthalocyanine compounds were matched with the wavelengths of semiconductor lasers. It was found that the absorption regions of vacuum sublimated thin films of vanadyl phthalocyanine (VOPc), tetra-pentyloxy phthalocyanine vanadyl (TPPcVO) and tetra-nonyloxy phthalocyanine vanadyl (TNPcVO) were between 580 and 850 nm. In the near-IR region, the absorbance and reflectivity of thin films of VOPc were greater than 50% and 20% respectively. The static optical recording test of the VOPc thin film showed that the write power was less than 10 mW with the write pulse width of 200 ns using an He-Ne laser as light source. The dynamic optical recording test of VOPc as a write-once read-many recording material on a 5.25 in optical disk indicated that the carrier-to-noise ratio (CNR) was greater than 45 dB.

Photophysical properties and optical limiting property of a soluble chloroaluminum-phthalocyanine

A chloroaluminum-phthalocyanine (AlCl-Pc) with tetra-alpha-butoxy chains (AlCl-Pc-OC4) has been synthesized and the photophysical parameters have been determined using steady-state and time-resolved absorption as well as emission spectroscopy. A luminescence from S2 excited state with long lifetime (5.71ns) is observed. A multi level model has been proposed to explain the photophysical processes after Soret-band excitation (lambdaex=355nm). The optical limiting performance for 532nm-7ns laser pulses of AlCl-Pc-OC4 has been investigated in THF solution. The sigmaex and ratio of sigmaex/sigma0 has been calculated. The good optical limiting performance is attributed to a reverse saturable absorption mechanism. It indicates that AlCl-Pc-OC4 could be promising candidates for optical limiting material.

Investigation of third-order nonlinearity of an azo dye and its metal-substituted compounds

Abstract The real part of third-order optical nonlinearity of an azo dye (2-(2-thiazolylazo)-5-diethylaminophenol, TAEP) and those of its copper- and cobalt-substituted compounds are measured by using femtosecond optical heterodyne optical Kerr gate technique at the wavelength of 647 nm. All the values are found to be negative. Those of Cu- and Co-substituted compounds are found to be larger than that of the metal-free dye by two and three orders of magnitude, respectively. A negative γ eff as large as 10 −29 esu is found in Co complex. We use a three-level model to characterize the nonlinear process, and suggest that π-electron delocalization in metal complex leads to an enhancement.

Synthesis and optical properties of an azo metal chelate compound for optical recording medium

Abstract An azo nickel chelate compound has been synthesized. Smooth thin films have been prepared by spin-coating. The absorption, transmission and reflection spectra of the films were measured. The optical constant (complex refractive index N = n + ik ) of the film on single-crystal silicon has been determined using scanning ellipsometer, and the complex dielectric function ( e ) as well as absorption coefficient ( α ) were then calculated. The optical recording medium was prepared by spin-coating on a PC substrate with aluminium as reflective layer. Dynamic optical recording test of the disc showed that the carrier-to-noise (CNR) of 45dB was obtained.

Metallized thiazolylazo dyes as optical recording materials

Abstract A series of metallized thiazolylazo dyes have been designed and synthesized. Smooth films on optical glass and single-crystal silicon were prepared using the spin-coated method. The UV-Vis absorption spectra of the dyes were measured in solution and in films. The optical constant (complex refractive index N = n + ik ) of the films on single-crystal silicon has been determined using a scanning ellipsometer. The variation of the complex refractive index, N , with wavelength, λ , was obtained. From the value of n , k and the thickness of the dye films, the variation of the reflectance vs dye film thickness was then calculated. Thermogravimetric analysis (TGA) and differential thermal analysis (DTA) of the nickel thiazolylazo dye showed a clear threshold of thermal decomposition with a sharp exothermic park. Static optical recording tests were carried out. The results show that the nickel thiazolylazo dye is more suitable for use in short-wavelength diode-laser optical recording.

Novel Langmuir—Blodgett films, consisting of amphiphilic zinc phthalocyanine and hydrophobic porphyrin

Abstract An amphiphilic zinc phthalocyanine (AmZnPc) containing long alkyl chains covalently attached to the positively charged macroring was synthesized. A monolayer of AmZnPc with equimolar meso-tetrakis-(4-tolyl)porphine (TTP) was spread on water from chloroform solution and transferred onto CaF 2 slides. Multilayers were also built up on these substrates. Surface pressure-area isotherms and UV—visible absorption spectra showed that the porphyrin molecules are arranged in the cavity between the long alkyl chains of AmZnPc in one layer of the Langmuir—Blodgett film. Polarized UV—visible spectroscopy indicated that there is no anisotropy in the layer plane and the AmZnPC macroring plane lies nearly parallel to the substrate surface.

Spectroscopic and optical properties of an azo-metal chelate dye as optical recording medium

Abstract The spectroscopic, optical and thermal properties of an azo-nickel chelate dye have been studied in solution and in thin films. Complex formation constant of the compound was evaluated spectroscopically in methanol. The optical constant (complex refractive index N = n + ik ) of the film on single-crystal silicon has been determined using scanning ellipsometer and the complex dielectric function e as well as absorption coefficient α were then calculated. Thermal decomposition with a sharp exothermic peak was observed. The optical recording medium was prepared by spin-coating on a PC substrate with aluminum as reflective layer. Dynamic optical recording test of the disc gave a value of carrier-to-noise (CNR) of 45 dB, indicating that the azo-metal chelate dye is a promising candidate for use as optical recording medium.

Spectroscopic properties of phthalocyanine dyes for optical recording medium

Phthalocyanine dyes with various central metal atoms and different substituents showing improved spectroscopic properties to match the output of GaAs diode-laser have been synthesized. Smooth thin films have been prepared by spin- coating technique. Solvent-vapor induced crystallization of VOPc(OC3H7)4 has also been studied. The results showed that the VOPc(OC3H7)4 primarily deposited on glass substrate as an amorphous form. However, the dyes were changed to crystalline form by exposure to appropriate solvent vapors. The polymorphs of the VOPc(OC3H7)4 were investigated by visible absorption and IR spectroscopy, X-ray diffraction and high resolution electron microscopy. The optical recording performances of the thin films were also reported.

Optical recording performance of phthalocyanine thin films

Optical recording performance of phthalocyanine thin films as write-once read-many recording media has ben investigated. The retrieval of information from the disk utilizing a phthalocyanine thin film has been successfully realized.