O. L. Bourne

Multifunctional single-walled carbon nanotube–cellulose composite paper

Single-walled carbon nanotubes (SWCNTs) have been used as fillers to produce electrically conductive composite papers. While conductive composite papers have been made using other fillers, they either suffer from instability or low conductivity. Using simple papermaking techniques, we have made SWCNT–cellulose composite paper which possesses a conductivity of 3 × 10−2 S cm−1 and is comparable to or exceeds other reports of carbon nanotube–cellulose papers made by layer-by-layer assembly. These composite papers are multifunctional, having both improved electrical conductivity and enhanced flame retardant properties over the control paper.

Laser isotope separation of zirconium atoms cooled in a supersonic beam

Abstract A method for the separation of zirconium isotopes based on a two-colour photoionisation scheme is reported. Laser vaporisation of a zirconium rod together with cooling by supersonic expansion in a molecular beam apparatus provides a high concentration of atomic zirconium. Hyperfine splitting in the z3F2 ← a3F2 transition of atomic zirconium allows isotopically selective absorption of a first photon. Subsequent absorption of two photons, the first resonantly, gives selectivities of = 100 for ionisation of 91Zr.

A high resolution laser induced fluorescence study of a supersonic zirconium atom beam

Abstract We report high resolution fluorescence excitation spectra of zirconium atoms formed via pulsed laser evaporation of a zirconium metal rod. Results obtained from an optogalvanic study are also commented upon. Quantitative values for isotope and hyperfine shifts for the transition (4d 2 5s 2 )a 3 F 2 →(4d 2 5s5p)z 3 F 0 2 at 613.6 nm are given. The magnitude of the obse rved hyperfine shifts are consistent with requirements for laser isotope separation.

Digital etching of III-V multilayered structures combined with laser ionization mass spectroscopy : photon-assisted depth profiling

A photochemical method for depth profiling multilayered structures of GaAs and AlGaAs is presented. The process combines surface chlorination reactions using molecular chlorine, desorption of surface chlorides, and single step laser ionization time‐of‐flight mass spectroscopy. Pulsed excimer lasers are used for the desorption and ionization steps. The etch rates approached a monolayer per pulse for both substrates. Prospects for improving the resolution of the process in the lateral and vertical dimensions are discussed.

Pressure tuned single longitudinal mode dye laser

Abstract The design and construction of a pressure tuned single longitudinal mode (SLM) dye oscillator is described. The oscillator had a pressure tuned range of ⩾ 3.75 cm −1 and a time average linewidth of 0.019 cm -1 . The output of the oscillator could be increased by four orders of magnitude in an amplifier chain which incorporated a phase conjugate reflector to control the build up of amplified spontaneous emission. Focusable power of > 100 GW/cm 2 were obtained at a linewidth of 0.022 cm -1 .

Generation of 50 ps 308 nm pulses by means of truncated stimulated brillouin scattering

Abstract A frequency doubled dye laser system, incorporating a single longitudinal mode oscillator, followed by a single stage XeCl amplifier has yielded truncated stimulated Brillouin scattering (TRUBS) pulses of ≈50 ps duration and is potentially capable of providing significantly shorter pulses.

Depth profiling a III–V multilayered structure with an excimer laser

A multilayered structure of GaAs and AlGaAs was depth profiled using the technique of digital etching. A single excimer laser (KrF) was used to control the etch rate and to identify each layer by monitoring the Ga ions generated during the desorption process. The Ga ions were the only ions observed and were only generated when the photon flux was in the GaAs layer. The etch rate, 0.9 monolayers (2.5 Å) per pulse, was constant with depth. The overall layer recognition resolution was 45 monolayers.

Narrow bandwidth coherent VUV spectroscopy of the Kr 123.58 nm line

Abstract Coherent VUV light has been generated with a bandwidth of 0.02−0.04 cm -1 at 80917 cm -1 (123.6 nm) using four-wave sum frequency mixing of a pulse amplified, cw ring dye laser and a single longitudinal mode, pulsed dye laser. This VUV light was used to study the isotope structure of the Kr 123.58 nm line.

High Spectral Brightness Dye Lasers

In this report we give a brief overview of the methods presently available for the direct generation of high peak power (> 1 MW), high spectral brightness (Δν 1000) pulse amplifier chain.

Generation Of Subnanosecond Excimer Laser Pulses By Means Of Stimulated Brillouin Scattering In Liquids

The development of truncated stimulated Brillouin scattering (TRUBS) as a means of producing subnanosecond laser pulses is described. Recent experiments carried out with a frequency doubled excimer-pumped dye laser system, incorporating a single longitudinal mode oscillator, and a single stage of amplification in a XeCℓ gain module have yielded subnanosecond (-100 ps) UV pulses with an energy of -2 mJ as well as lower energy pulses shorter than 50 ps. The technique shows considerable promise as a reliable means of obtaining excimer laser pulses in the 10-50 ps range.