Switching of the triplet excited state of the C60-dimethylaminostyryl BODIPY dyads/triads

Switching of the triplet excited state of BODIPY-C60 dyads/triads with acid/base was studied with nanosecond time-resolved transient difference absorption spectroscopy.

Improvement of DOAS Technology in the Application of Mixed Gas Quantitative Analysis

According to difference absorption spectrum mixed gas absorption spectrum in technology overlapping problem, a DOAS technology based on the PSO and LS-SVM fusion method was proposed. First, SO2, NO respectively to construct a quantitative analysis model by LS-SVM, And then, using PSO is strong optimization ability of least square support vector machine (SVM) the optimization of the parameters of the algorithm, and then, LS-SVMs parameter are optimized with PSO of the powerful searching ability, Finally, rebuilt the quantitative analysis model. Experiments show that using the improved DOAS method is feasible in solving the mixed gas spectrum overlap problem which has certain practical significance.

Estimasi Produk Degradasi Ekstrak Kasar Pigmen Alga Merah Kappaphycus alvarezii (Doty) Doty Varian Merah, Coklat, dan Hijau: Telaah Perbedaan Spektrum Serapan

Penelitian ini bertujuan untuk mengestimasi produk degradasi pigmen ekstrak kasar alga merah Kappaphycus alvarezii (Doty) Doty varian merah, coklat dan hijau yang terbentuk selama perlakuan iradiasi dan pemanasan, melalui perbedaan spektrum serapannya. Ketiga varian diekstraksi menggunakan 100% metanol. Uji fotostabilitas ekstrak pigmen dilakukan dengan iradiasi menggunakan lampu Volpi intralux 4100 pada intensitas cahaya 39300 lux, 56700 lux dan 76400 lux. Lama waktu penyinaran 0, 5, 10, 15, dan 20 menit. Sedangkan uji termostabilitas dilakukan pada suhu 25 dan 90 ° C selama 0, 3, 6 24, dan 48 jam. Pola spektra diukur pada panjang gelombang 300-800 nm sebelum dan sesudah perlakuan dengan spektrofotometer UV-Tampak Shimadzu 1700. Data dianalisis dengan SPINA Versi 3, untuk memperoleh intensitas maksimum dan perbedaan spektra serapan. Hasil penelitian menunjukkan bahwa produk degradasi pigmen ekstrak kasar alga merah K. alvarezii dapat diidentifikasi melalui spektrum serapan dan hasil perbedaan spektra serapan. Isomer cis karotenoid, karotenoid tidak berwarna, dan feofitin a diestimasi sebagai produk degradasi yang terbentuk selama perlakuan iradiasi dengan intensitas cahaya 76400 lux dan perlakuan pemanasan pada suhu 90°C selama 48 jam. Penurunan intensitas warna larutan pigmen juga mengindikasikan terbentuknya produk degradasi selama perlakuan. Kata kunci: Kappaphycus alvarezii, perbedaan spektrum serapan, produk degradasi The aims of this study were to estimate the degradation products of crude pigment extracts from red, brown, and green varieties of red alga Kappaphycus alverezii (Doty) Doty that formed during irradiation and heating treatment from their difference absorption spectra. All three variants were extracted using 100% methanol. The photostability assay of crude pigment extracts was conducted by irradiating the crude pigment extracts with a day light lamp (Volpi, Intralux 4100) at 39300 lux, 56700 lux and 76400 lux light intensity during 0, 5, 10, 15, and 20 minutes treatment, whereas the thermostability assay was performed at 25 and 90 °C for 0, 3, 6 24, and 48 hours. The absorption spectra of the crude pigment extract before and after each treatment were monitored successively at 300-800 nm using MultiSpec 1501 UV-VIS spectrophotometer. Data were analyzed with spina Version 3, to obtain maximum intensity and the difference absorption spectra. The results showed that the degradation products of crude pigment extracts from red alga K. alvarezii could be identified by absorption spectra and difference absorption spectra. Cis isomers carotenoids, colorless carotenoids, and feofitin-a were estimated as degradation product formed during the irradiation treatment with 76400 lux of light intensity and heating treatment at a temperature of 90 ° C for 48 hours. Decrease in the intensity of the color of pigment solution also indicates the formation of degradation products during treatment.Key words: Kappaphycus alvarezii, difference absorption spectra, degradation products

Difference Absorption Optical Fiber Methane Gas Sensor Based on FBG

In this paper, based on analysis of the near infrared spectral absorption of methane molecule and considering factors such as compatibility with the transmission characteristics of silica optical fiber and the price, using Fiber Bragg Grating (FBG) filters to replace the the traditional interference filter, a novel kind of all-fiber remote sensor utilizing FBG filters and 1.33μm high power light-emitting diode (LED) was developed for real time measurement of methane gas concentration. FBG has a low insert loss and can be produced easily compared with dielectric interference filters. Theory and experiment proved that the system has simple construct and high sensibility.

A Detection Circuit to Faint Signal for Difference Absorption Gas Sensor

ion: In gas difference absorption detecting system, the output electric signal is very faint and submerged in the background noise. In order to extract the faint signal covered by the background noise, we design the detective circuit aiming at how to restrain the noise and improve SNR of the system. In this paper, the detection circuit centering lock-in amplifier which reference signal frequency is automaticly followed is designed. The circuit adopts synchronization cumulating and locked loop technic, carries out frequency and phase aotomatic follow to the measuring signal by a locked loop circuit. The circuit not only avoids the tache taking reference signai from the modulator then adjusting the phase shif, but also improving signal-to-noise ratio more by synchronization cumulation.

Novel Optical Fiber Gas Sensing System Based on FBG Filtering

Based on law of Beer-Lambert, a novel optical fiber gas sensing system is designed to determine the concentration of gas. The narrow-band filtering characteristic of optical fiber Bragg grating is used by this system to produce the narrow spectrum light signal which is wanted in difference absorption measuring. The system has full optical fiber structure, which is mainly composed by super luminescent emitting diode (SLED), optical fiber of 10km, optical fiber gas detector, optical fiber isolator, optical fiber coupler network, optical fiber detecting grating, photoelectric detector and data processing unit. The aspheric objective optical fiber collimator is adopted by this system to compose optical fiber gas sensing detector, which enhances the optic stability of the detector, diminishes the injection loss and makes the echo signal of the optical fiber detector greatly diminished. Experimental data and results show that this system has its feasibility and it can be used for real time monitoring of gas concentration in the domains of colliery and natural gas station, etc.