Argon Ion Laser Wavelength Research Articles

Photochemically deposited surface relief gratings of an azo-dye-labeled phospholipid from the aqueous phase

Surface relief holographic gratings are fabricated on the polybutadiene-coated walls of a cell filled with an aqueous solution of an azo-dye-labeled phospholipid. A low power (2 mW) 488 nm argon ion laser wavelength is used. Laser-excited azo dye reacts to produce a permanent surface-relief pattern on the polybutadiene substrate. Gratings are recorded for varying concentrations of the phospholipid solution as well as laser intensity. Lithographic masks are used to show that the photochemical pattern on the substrate is an exact replica of the light intensity distribution, and so the technique can be used for holographic recording as well as for biomolecular applications.

The necessary requirements imposed on polar dielectric laser dye solvents

A laser Mach–Zehnder interferometeric technique is applied to measure the refractive index n and its thermo-optic coefficient d n/d T for five important pure polar dielectric laser dye solvents (water, methanol, ethyleneglycol, butanol and acetic acid). The measurements are carried out using the argon-ion laser wavelength 514.5 nm, and He–Ne laser of λ=632.8 nm. Applying the empirical relationship of Cauchy between the refractive index and wavelength, the following properties are calculated and represented: The refractive index, the thermo-optic constant −d n/d T, the optical dispersion −d n/d λ as a function of wavelength and Cauchy's constants against temperature. On the other hand, a discussion for comparison between the investigated solvents are given.

Resonant Nonlinear Optical Studies on Porphyrin Derivatives

The nonlinear optical properties of three porphyrin derivatives (T3,4 BCEMPP, T4 CEMPP and TPP) doped in boric acid glass were probed using the Z-scan technique at different argon-ion laser wavelengths. The nonlinear transmission characteristics of T3,4 BCEMPP and T4 CEMPP exhibit saturable absorption at 457.9 nm and 476.5 nm while these are dominated by excited state absorption at 488.0 nm. However, in the case of TPP, the excited state absorption dominates the nonlinear characteristics except at 457.9 nm. The experimental observations are explained by using the four-level saturable absorber model. Saturation intensity, excited state absorption cross-section, light-induced changes in the absorption and the refractive index along with its sign were determined at these argon-ion laser wavelengths. Furthermore, optical limiting characteristics of these samples were studied. The observed limiting action is consistent with the Z-scan studies.

Z-scan studies in fluorescein-doped boric acid glass

The non-linear response of fluorescein-doped boric acid glass was probed using the Z-scan technique. A striking contrast was observed in its non-linear transmission characteristics at different argon-ion laser wavelengths. The non-linear transmission characteristics exhibit strong saturation behaviour at 457.9nm whilst at 476.5nm and 488.0nm the response is dominated by intense excited state absorption. The experimental observations are explained using the four-level saturable absorber model. The excited state absorption cross-section, saturation intensity, light induced absorption and refraction changes have been determined along with the sign of the non-linearity at various argon laser wavelengths. The optical limiting characteristics of fluorescein at 476.5 nm and 457.9 nm are also reported. The behaviour of the sample was in agreement with the Z-scan observations.

Laser-assisted chemical vapor deposition of nickel and laser cutting in integrated circuit restructuring

Laser-assisted chemical vapor deposition (LCVD) of nickel from Ni(CO)4 has been utilised for the restructuring of integrated circuit (IC) interconnections. Nickel lines were deposited on a SiO2 passivated IC to achieve new local interconnections between integrated circuit structures. Depositions were carried out over the pressure range of 0.2 to 2.2 mbar of pure Ni(CO)4 buffered in 0 to 800 mbar He. Argon ion laser wavelengths of 488 and 514.5 nm, laser power of 50-150 mW and a laser scan speed of 80 μm/s were utilised for the deposition. The morphology and chemical contents of the deposited interconnection microstructures was examined by AFM, optical microscopy and LIMA. The resistivity of the deposited lines was found to be close to the nickel bulk resistivity. The utilisation of Nd: YAG and XeCl excimer lasers in the cutting of Al and Mo conductor lines for integrated circuit modification is also described.

Growth and High Reflectivity Self-Pumped Phase Conjugate of Cu-Doped KNSBN Crystal

The Cu-doped KNSBN crystals have been grown. The self-pumped phase conjugate mirrors of Cu-doped KNSBN crystals have been demonstrated. The phase conjugate reflectivity reaches as high as 68% for the crystal with 0.04 wt.% Cu-doped. The phase conjugate reflectivity and its response time were also measured as a function of the argon-ion laser wavelengths.

Surface-enhanced Raman scattering from molecules adsorbed on gallium surfaces

We report the first observation of surface-enhanced Raman scattering (SERS) for molecules adsorbed on gallium surfaces. The gallium surfaces were prepared in UHV by depositing gallium vapor on cold copper substrates. The enhanced Raman spectra could be generated by all argon ion laser wavelengths between 457.9 and 514.5 nm but the magnitude of the enhancement was at least three times greater at 457.9 nm excitation than at 514.5 nm excitation. At 514.5 nm excitation, gallium SERS is about an order of magnitude weaker than silver SERS at the same excitation wavelength.

BSKNN as a self-pumped phase conjugator

Self-pumping has been observed in a cerium-doped Ba(2-x)Sr(x)K(1-y)Na(y)Nb(5)O(15) (BSKNN) crystal at four argonion laser wavelengths. Phase-conjugate reflectivities as high as 30% were measured with response times inversely proportional to the 0.5 power of the input intensity. The response time for beam fanning in the crystal was determined to be inversely proportional to the 0.82 power of the input intensity.

Atomic fine-structure state selectivity for the collision-induced photodissociation of the B 1Π u state of Li 2

In the collisionally induced dissociation of the photoexcited B 1Π u state of Li 2, which has Li(2 2P) + Li(2 2S) as products, it is found that the 2 2P 3 2 fine-structure state is preferentially produced. The 2 2P 3 2 and 2 2P 1 2 atomic Li state production was measured by observing the fluorescence produced upon excitation to the 3 2D 5 2 and 3 2D 3 2 states using a single-mode cw tunable dye laser. The 2 2P 1 2 /2 2P 3 2 ratio of the excited atomic lithium was measured as a function of helium gas pressure with 457.9, 476.5, or 488.0 nm argon ion laser wavelengths used to produce the B 1Π u state excitation.

Magnetic resonance raman optical activity of ferrocytochrome e at different laser wavelengths

Magnetic field induced resonance Raman circular intensity differential spectra are reported for the two argon ion laser wavelengths (514.5 and 501.7 nm) that fall within the β electronic absorption band of ferrocytochrome c. The signs and magnitudes of the effects are completely different in the two sets of spectra, and might be related to the slope of the corresponding magnetic circular dichroism band envelope at the excitation wavelength.

Inelastic photon scattering by a polyatomic molecule: NO2

When NO2 is illuminated by monochromatic visible light, the frequency distribution of the photons scattered inelastically consists of discrete spikes superimposed on a broad continuum. This scattered intensity has been compared with the Raman scattering from N2 with respect to the following variables: (i) argon-ion laser wavelengths; (ii) NO2 pressure; (iii) air pressure. The intensity scattered by a molecule of NO2 is found to be 116 times the Raman intensity from a molecule of N2, NO2 being in air at STP; (the broad continuum intensity from NO2 was measured at 720 cm−1, from the 4880-Å laser wavelength, with a spectrometer slit width of 10 Å). The quenching constant for the NO2 continuum by air is found to be 67 Torr−1. The observed dependence of the scattered intensity on wavelength and pressure can be explained qualitatively in terms of an expected dense distribution of energy levels in NO2.

Model Potential Calculation of the Raman Tensor for Be, Mg, and Zn

A model potential calculation of the first derivative of the electronic polarizability with respect to an atomic displacement for Be, Mg, and Zn is presented. The magnitudes of these derivatives, which govern the intensity of the first-order Raman effect in the corresponding crystals at the argon-ion laser wavelength of 4880 \AA{}, are 39.7 ${\mathrm{\AA{}}}^{2}$ for Be, 11.2 ${\mathrm{\AA{}}}^{2}$ for Mg, and 18.9 ${\mathrm{\AA{}}}^{2}$ for Zn. The dependence of the real and imaginary parts of the polarizability derivative on the frequency of the incident light has also been calculated for these crystals.