A Versatile Multiple-Pass Raman System for Industrial Trace Gas Detection.

The fast and in-line multigas detection is critical for a variety of industrial applications. In the present work, we demonstrate the utility of multiple-pass-enhanced Raman spectroscopy as a unique tool for sensitive industrial multigas detection. Instead of using spherical mirrors, D-shaped mirrors are chosen as cavity mirrors in our design, and 26 total passes are achieved in a simple and compact multiple-pass optical system. Due to the large number of passes achieved inside the multiple-pass cavity, experiments with ambient air show that the noise equivalent detection limit (3σ) of 7.6 Pa (N2), 8.4 Pa (O2) and 2.8 Pa (H2O), which correspond to relative abundance by volume at 1 bar total pressure of 76 ppm, 84 ppm and 28 ppm, can be achieved in one second with a 1.5 W red laser. Moreover, this multiple-pass Raman system can be easily upgraded to a multiple-channel detection system, and a two-channel detection system is demonstrated and characterized. High utilization ratio of laser energy (defined as the ratio of laser energy at sampling point to the laser output energy) is realized in this design, and high sensitivity is achieved in every sampling position. Compared with single-point sampling system, the back-to-back experiments show that LODs of 8.0 Pa, 8.9 Pa and 3.0 Pa can be achieved for N2, O2 and H2O in one second. Methods to further improve the system performance are also briefly discussed, and the analysis shows that similar or even better sensitivity can be achieved in both sampling positions for practical industrial applications.

Absolute measurement approach for crystal growth height based on a polarization-synchronized phase-shifting interferometer.

The quality of the solid deuterium-deuterium (D-D) layer in the inertial confinement fusion (ICF) target plays a vital role in the success of fusion experiments. A good understanding of how the quality is affected by the unstable growth of D-D crystal is required. This article provides an approach of measuring D-D layer absolute height in real time by combining monitoring algorithms and a synchronous phase-shifting interferometer. In the approach taken, a real-time monitoring technology, in which an antivibration algorithm is added, is used to get an absolute height of monitoring zone, overcoming the inability to accurately detect the saltus step in the interferometric measurement. Meanwhile, the polarization-synchronized phase-shifting technology is propitious to retrieve the D-D height distribution in a whole interferogram. Consequently, the categorical altitude of the D-D layer in entire crystalline regions can be obtained. Simulation analysis together with experiments have proved that a non-contact, rapid, and high-precision measurement of the D-D crystal absolute height can be realized by using the interferometer and method proposed.

A Simple Electrochemical Route to Access Amorphous Co-Ni Hydroxide for Non-enzymatic Glucose Sensing.

Among the numerous transition metal hydroxide materials, cobalt- and nickel-based hydroxides have been extensively studied for their excellent electrochemical performances such as non-enzymatic electrochemical sensors. Binary cobalt-nickel hydroxide has received extensive attention for its exceptionally splendid electrochemical behaviors as a promising glucose sensor material. In this work, we report the synthesis of three-dimensional amorphous Co-Ni hydroxide nanostructures with homogeneous distribution of elements via a simple and chemically clean electrochemical deposition method. The amorphous Co-Ni hydroxide, as a non-enzymatic glucose sensor material, exhibits a superior biosensing performance toward glucose detection for its superior electron transfer capability, high specific surface area, and abundant intrinsic redox couples of Ni2+/Ni3+ and Co2+/Co3+/Co4+ ions. The as-synthesized amorphous Co-Ni hydroxide holds great potential in glucose monitoring and detection as non-enzymatic glucose sensors with high sensitivity 1911.5 µA mM-1 cm-2 at low concentration, wide linear range of 0.00025-1 mM and 1-5 mM, low detection limit of 0.127 µM, super long-term stability, and excellent selectivity in 0.5 M NaOH solution.

[Study of IR Property of Glow Discharge Polymer (GDP)].

To achieve the object of NIF ignition , it is required to prepare high density fuel targets . For DD layer, IR-layering can be used to improve its surface roughness. In this paper, glow discharge polymer (GDP) flat films and capsules were synthesized. The IR absorptive properties of GDP were thoroughly studied by using infrared spectrometer and microscopy while the extinction coefficients of GDP flat film at specific wavelengths were obtained. By comparing absorption properties of flat films and capsules, it is found that thermal treatments can lower the OH content of GDP and thus improve IR layering of DD ice. Finally, the needed IR power of integration sphere were estimated by using data obtained for future DD layering experiments in this paper. The results have laid a solid foundation for the implementation of DD IR layering.

Role of intersystem crossing in the fluorescence quenching of 2-aminopurine 2'-deoxyriboside in solution.

2-Aminopurine is a fluorescent probe widely used to study local dynamics as well as charge and energy transfer reactions in DNA/RNA. Despite its broad utilization, the nonradiative relaxation pathways responsible for the variation in its fluorescence quantum yield and fluorescence lifetime in different solvents are still under scrutiny. In this work we use steady-state absorption and emission spectroscopy and broad-band transient absorption covering the time scale from femtoseconds to microseconds to investigate the excited-state dynamics of 2-aminopurine 2'-deoxyriboside (2APdr) in acetonitrile, ethanol, and aqueous buffer solution at pH 7. It is shown that up to ~40% of the initial excited-state population decays by intersystem crossing to the triplet state depending on the solvent used, thus competing effectively with fluorescence emission. Furthermore, the rate of formation and yield of the triplet state depend sensitively on the hydrogen-donor ability and polarity of the solvent.