Chuanliang Li

Taiyuan University of Science and Technology · Department of Physics

We demonstrate a simple method to measure electric field intensity by using doublet electromagnetically induced transparency (EIT) spectra of cold Rb Rydberg atoms, where the frequency of coupling laser needs not to be locked. Based on the Stark splitting of Rb Rydberg state, 10D 3/2 , under electric fields and the corresponding calculated polariza...

Flour is an essential ingredient in human daily diet, thus it is crucial to measure its moisture content. However, the detection of flour moisture content at present is time-consuming and labor-intensive, which makes it impossible to measure moisture quickly. This study demonstrates the measurement of moisture content in flour via gas in scattering...

In this paper, an ultra-wideband solar absorber consisting of a four-layer structure of Al 2 O 3 -TiN-Al 2 O 3 -Ti is proposed. The proposed absorber achieves an average absorption of 97.85% in the wavelength range of 250–2000 nm (49.96% improvement over the reference planar structure), and its bandwidth of absorption over 90% is even as high as 17...

The temperature measurement of Sulfur dioxide (SO2) is a crucial parameter for accurately determining its concentration, particularly in high‐temperature environment. Herein, it is realized by using three different techniques, which are direct absorption spectroscopy, wavelength modulation spectroscopy and non‐calibration wavelength modulation spec...

2,4- and 2,6-isomers of toluene diisocyanates (2,4-TDI and 2,6-TDI) are important raw materials in the polyurethane industry. These reactive compounds associate even under ambient conditions to form oligomers, changing the physicochemical properties of the raw material. Kinetically and thermodynamically relevant dimerization reactions were selected...

A resonant photoacoustic spectrometer (PAS) was developed for detecting trace atmospheric CH4. The sensitivity of the PAS was significantly increased via a Herriott-type multipass cell with a beam pattern concentrated in the cavity. The effective optical pathlength of the PAS can be optimized to 6.8 m with 34 reflections and a diameter of 6 mm. A d...

Four lowest electronic states (X2Σ+, A2Σ+, B2Π and C2Σ+) of the HeH radical are investigated by performing high-precision ab initio calculations. Potential energy curves of HeH are calculated using the internally contracted multireference configuration interaction method in combination with the basis set of aug-cc-pV6Z. To improve the accuracy, add...

Plasma temperature and electron density are two important parameters describing the characteristics of plasma. The Aluminum plasma is produced by laser‐induced breakdown spectroscopy and its emission spectra are observed by a spectrometer with high resolution. Based on its discrete ultraviolet lines, pair‐line Boltzmann (PLB) approach is proposed t...

The laser ultrasonic technique (LUT) enables the analysis of complex signals and the extraction of the features of defects. The time‐domain features can be used to quantify various defects, but are negatively affected by the coupling efficiency, measurement noise, and surface roughness during LUT. This paper describes defect analysis methods based...

Hyperfine structures and the field effects of IBr molecule in its rovibronic ground state are theoretically studied by diagonalizing the effective Hamiltonian matrix. Perturbations of high- J levels up to 4 are taken into account when studying the hyperfine sub-levels of the J = 0 level, and thus, an 80 × 80 matrix is constructed and solved. Some o...

The flow and evaporation of liquid films widely exist in various industrial fields. The investigation into liquid films is essential to design and optimize the relevant industrial processes. In this work, a simultaneous measurement method of liquid film thickness and temperature on metal surface based on diode laser absorption spectroscopy (DLAS) w...

A photoacoustic spectroscopy sensor for nitrogen dioxide (NO2) detection was presented based on a high‐power broadband blue diode laser emitting at 446 nm. An optical chopper was replaced by a transistor transistor logic modulation signal generated by the signal generator to reduce mechanical noise. The detection limit of NO2 sensor system reached...

A palm-sized laser spectrometer has been developed for detecting trace gases based on tunable diode laser absorption spectroscopy in combination with a novel double-layer toroidal cell. With the benefit of a homemade electronic system and compact optical design, the physical dimensions of the sensor are minimized to 24 × 15× 16 cm3. A toroidal abso...

Continuously alternating loads and environmental temperature fluctuations can easily cause material aging and fatigue defects in some in-service infrastructures. In order to improve the load-bearing capacities of these infrastructures and prevent unexpected accidents, a flexible continuous detection system that can evaluate the health of these stru...

We developed a type of toroidal multi-pass cell with multi-layer patterns based on the off-axis model. The effective path length of the original toroidal multi-pass cell is extended several roundtrips in comparison with the single-layer pattern, since the inner surface of the toroidal multi-pass cell is more efficiently utilized. The light pattern...

We present resonance enhanced two-photon ionization (RETPI) spectrum between 14500 and 15850 cm−1 for ultracold ground state ⁸⁵Rb¹³³Cs molecules. With an assistant of optical pumping from one 1070nm laser, (2)1Π1←X1Σ+ electronic transition is distinguished from (4)3Σ+←a3Σ+ and (3)3Π←a3Σ+ transitions. Some observed RETPI spectra are globally assigne...

Nitric oxide (NO) is an important product released by cigarette burning with significantly negative effects to both environment and human health, but it is hard to be measured in-situ in the process of burning. In this paper, we report a tunable diode laser absorption spectroscopy (TDLAS) set-up using a quantum cascade laser emitting at 5.24 μm to...

Compared with light intensity measurements of turbid liquids based on direct or lock-in amplification methods, the square excitation method (SEM) can be used to obtained abundant information from both the time- and frequency-domains. Voltage-based turbidimetry in the time domain (The voltage readout here refers to the signal obtained directly by th...

Hydrogen sulfide (H2S) is a highly toxic gaseous component of natural gas that poses a significant hazard during the use of natural gas for domestic purposes; therefore, a high-sensitivity, on-line detection method is extremely important to ensure its safety for domestic use. In this work, a portable sensor was developed based on near-infrared tuna...

The leakage detection system of vials based on two-line water-vapor tunable diode laser absorption spectroscopy (TDLAS) developed in our previous work was first employed to investigate the instantaneous leakage processes of sealed vials. It showed that the leakage states of the vials with medicines cannot be accurately determined in a short time af...

As a common hazard, coal spontaneous combustion (CSC) causes the loss of coal in piles and mines. To rapidly and reliably forecast CSC, a portable and powerful detection system based on a laser spectroscopic technique is proposed, to precisely measure gaseous inhibitors; the technique uses a single, distributed-feedback diode laser emitting at 2.33...

A laser-based spectrometer with a physical size of 60× 30 ×25 cm³ has been developed to continuously monitor CO and CH4 in atmosphere based on tunable diode laser absorption spectroscopy (TDLAS). Two neighboring lines of CO and CH4 around 2.3 μm were selected as candidates for simultaneous measurement by a single diode distributed feedback (DFB) la...

Coal spontaneous combustion (CSC) is a common hazard in coal mines and a significant reason for the loss of coal in stockpiles and mines. To investigate the oxidation and release of gas due to of CSC, a miniature purpose-built laser-based sensor system capable of precise gas measurement and data processing was configured. A distributed feedback (DF...

The simultaneous measurements of multiple parameters (film thickness, temperature, etc.) of the liquid films are crucial for the design and optimization of relevant industrial processes. Here, a sensor based on diode-laser absorption spectroscopy (DLAS) was developed to simultaneously measure liquid water film thicknesses and temperatures by combin...

In Traditional Chinese Medicine (TCM), moisture content (MC) inspection using voltage level or a lock-in amplifier, with a features-based near-infrared light-emitting diode sensor is possible. Abundant absorption response in a wide frequency range and information in both the time-domain and frequency-domain can be obtained, with the square excitati...

We report high-resolution photoassociation (PA) spectra of RbCs in the 2(0−) long-range state. Transitions to more than 50 vibrational levels were recorded with the largest binding energy being 507.5 cm−1. By fitting the experimental transition frequencies to the improved LeRoy-Bernstein formula, the C6 coefficient for the potential energy curve of...

Quantum time-dependent wave-packet calculations have been carried out to explore the state-to-state dynamics of the ion-molecule (H⁻ (D⁻),HD) collisions on two accurate ab initio potential energy surfaces in the collision energy range 0.2 – 1.2 eV. Total and final state-resolved integral and differential cross sections are elaborated in detail. The...

The selective catalytic reduction and non-selective catalytic reduction (SCR/SNCR) are the most popular de-NOx processes for coal-fired power plant, where the real-time temperature is a significant parameter. A new developed tunable diode laser spectroscopy used for measuring the temperature of ammonia (NH3) in the process of SCR/SNCR influenced by...

Long range intermolecular interaction potential surface of CaF ( ² σ ⁺ ) was simulated by employing the MOLPRO program and using the RCCSD(T)/def2-TZVP theory. The predicted data were further fitted to obtain the collision crosssection. The elastic collision cross-section of CaF at the temperature around 2 mK is as high as 6.5×10 ⁹ cm2 and the coll...

The signals processing algorithm is presented based on laser spectroscopy direct absorption signal (DAS) and wavelength modulation spectroscopy (WMS) for the trace carbon monoxide (CO) measurement. The simulated transmittance data of the pure CO gas are from the HATRAN database. The DAS intensity, appending WMS 1-f and WMS 2-f signal intensities ar...

A distributed feedback laser-based carbon monoxide (CO) sensor has been developed for early warning detection of fire. The sensor, based on a system-on-chip with high-performance 32-bit microcontroller (MCU), features a digital lock-in amplifier (DLIA) for wavelength modulation spectroscopy (WMS) to improve detection sensitivity. The ramp scanning...

We report a multi-pass tunable diode laser absorption spectrometer based on the frequency-modulation spectroscopy (FMS) technique. It has the advantage of high scan speed and is immune to the etalon effect. A multi-pass Herriott-type cell was used in the spectrometer to increase the effective optical length to 17.5 m and compact the physical dimens...

A low-noise, low power, high modulation-bandwidth design integrated laser current and temperature driver with excellent long-term stability is described. The current driver circuit is based on the Hall-Libbrecht design. A high sensitivity and a stable driver current were obtained using a differential amplifier and an integral amplifier. The set-poi...

Tunable diode laser absorption spectroscopy (TDLAS) is an important technique for trace gas detection. The sensitivity of TDLAS system, especially for multi-pass absorption, is usually limited by optical fringes. It is an effective approach to suppressing optical fringes of spectral lines using digital filtering. The parameters derived from filteri...

We propose to utilize the Σ1−1Σ electronic transition system for direct laser cooling of heteronuclear diatomic molecules. AgH, as well as its deuterium isotopolog AgD, is used as an example to illustrate the cooling schemes. Potential-energy curves and relevant molecular parameters of both AgH and AgD, including the spin-orbit constants and the el...

Fire poses a significant risk to the safety, health, and property of people around the world. However, traditional ‘‘point sensor’’ fire detection techniques for indoor buildings based on air particles, air temperatures, and smoke have a low sensitivity, long response time, and poor stability. Therefore, video-based fire detection has become a part...

The concentration of titanium element in the ferroalloys was measured by laser induced breakdown spectroscopy. The maximum spectral signals were observed at the output energy of pulse laser at 50 mJ and the delay at 1 μs. Under this circumstance, traditional calibration method (TCM) and internal standard method (ISM) with Fe Ⅰ 438.35 nm and Fe Ⅰ 42...

A resolved line pair was selected for simultaneous measurement of carbon monoxide (CO) and carbon dioxide (CO2) in the near-infrared (NIR) region. The spectral lines of CO and CO2 at 1.578 µm were measured by wavelength modulation spectroscopy (WMS)-2f and the absorption was enhanced with a multipass absorption cell. The white noise was further red...

The forbidden transitions of I2⁺ may be used to measure the variations of α and μ constant in an enhanced sensitivity. We analyze the rotational spectrum of I2⁺ between 11860 and 13100 cm⁻¹ and assign 5759 lines to 31 bands in an A²Π3/2-X²Π3/2 system. The accurate rotational molecular constants of 5 levels in X²Π3/2 state and 9 levels in A²Π3/2 sta...

Nitric oxide (NO) radicals in the a ⁴Π state were produced by discharging the mixture of NO gas and helium at the audio frequency. In the near infrared region, the spectra of the b ⁴Σ⁻ - a ⁴Π system of the NO radical were studied by optical heterodyne - concentration modulation laser absorption spectroscopy. More than one hundred and thirty lines a...

The P(4) line of 3-0 band for CO gas in different pressures and concentrations was measured by employing tunable diode laser absorption spectroscopy combined with balanced difference detection technology. Due to the immunization to the common-mode noise of fluctuation of laser intensity, drifts of temperature and mechanical vibrations, the sensitiv...

Based on consistent basis set aug-cc-pV5Z, five low-lying potential energy curves and transition dipole moments X²∑⁺, A²Π, B²∑⁺, a⁴Π and b⁴∑⁺ of BD⁺ are calculated by using internally contracted multi-reference configuration interaction approach. According to the calculation results, ro-vibrational levels of theses electronic states are derived thr...

Wavelength modulation spectroscopy (WMS) combined with a multipass absorption cell has been used to measure a weak absorption line of carbon monoxide (CO) at 1.578 µm. A 0.95m Herriott-type cell provides an effective absorption path length of 55.1 m. The WMS signals from the first and second harmonic output of a lock-in amplifier (WMS-1 f and 2 f,...

CF⁻ anion is very important for collisional ionization reactions, electron transfer from Rydberg atoms and electron attachment. Potential energy curves (PECs) of five low-lying excited electronic states, X³Σ⁻, a¹Δ, b¹Σ⁺, A³Π and c³¹Π of CF⁻, are calculated by using the internally contracted multireference configuration interaction (icMRCI) approach...

We present a theoretical study of the bichromatic force exerted on magnesium monofluoride (MgF), in which we have considered the complex vibrational and rotational levels and the effects of small internal splittings and degeneracies, including fine and hyperfine structures and the magnetic quantum numbers. We calculate some parameters used in the M...

A novel resonantly enhanced Bragg-scattering (REBS) spectroscopy from a population difference grating (PDG) is reported. The PDG is formed by a standing-wave (SW) pump field, which periodically modulates the space population distributions of two levels in the 87Rb D1 line. Then, a probe beam, having identical frequency and orthogonal polarization w...

With the rapid development of social economy, the environmental pollution and the ecological destruction are continuously deteriorating while sudden environmental pollution incidents occur frequently. Real-time monitoring harmful gases of the air take advantages of spectroscopic techniques for concentration measurement. Multipass optical cells are...

Six low-lying states (X2Σ+ g, A2Πu, B2Σ+ u, 4Σ+ g, 4Πu and 4Σ+ u) of C- 2 anion are studied by highly correlated ab initio calculations. The potential energy curves (PECs) are computed in the internuclear separation from 0.8 to 5.0 Å using the complete active space self-consistent field method, and then performing the internally contracted multiref...

The defect classification is investigated by using features-based giant-magnetoresistive pulsed eddy current (GMR-PEC) sensor. The power spectrum density of the intrinsic mode functions (IMFs) is extracted as the classification feature, considering the disadvantage of selecting a wavelet base determined in previous work on spectral analysis combine...

Random variation in temperature field causes refractive index fluctuation in the atmosphere. Wind velocity affects atmosphere turbulence dynamic characteristic. Thus, it forms optical turbulence effects and influences atmospheric laser transmission. Based on this principle, a modified Herriott type of long-optical-path atmospheric turbulence simula...

Using multi reference configuration interaction (MRCI) method, with aug-cc-pV5Z, aug-cc-pv6z, aug-cc-pcv5z, aug-cc-pcv6z basis sets etc., the single point energy of the ground state and the first excited state and second excited state of C⁻2 are calculated. Then LEVEL program is used to fit out the spectroscopic constants of three states. Results o...

We present a Herriott-type multipass laser absorption spectrometer enhanced by optical heterodyne detection. The proposal is demonstrated by measuring the spectra of water vapor molecule in the region from 12247.6873 to 12249.6954 cm-1. Compared with direct absorption spectroscopy, the signal-to-noise ratio is improved nearly one magnitude of facto...

Due to the weak absorption of H2O in the near infra red region, the frequency modulation (FM) is one of good technologies to increase the sensitivity of detection. This method is used to study the absorption spectra of water-vapor in the region around 814.65 nm. Compared to direct absorption method, the signal-to-noise of spectral signal is enhance...

The main objective of this paper is to precisely classify surface and subsurface cracks and cavities using a feature-based giant magnetoresistive pulsed eddy-current (PEC) sensor. Based on the author’s previous work involving amplitude spectral analysis combined with wavelet decomposition, the power spectral density analysis of the direct different...

The concentration of inhalable particle is an important indicator in atmospheric environment monitor. Based on Mie scattering extinction, a precise testing instrument which can measure the concentration of inhalable particles at the atmospheric was designed by three-wavelength method in combination with the algorithm of distributed function. The de...

We study the absorption spectra of water vapor by the 899-29 Ti:sapphire laser in the region between 12 252 -12 312 cm-1. Due to the weak absorption of H2O, a folded multi-pass optical path cell of Herriott-type is used to increase the sensitivity of detection. Totally, forty-three lines with intensity ranging around 10-24cm-1/molecule are recorded...

A identification system based on visible light communication using white light emitting diode (LED) of the miner's lamp has been proposed and demonstrated, in which the Tag and Reader have been designed and realized. The Manchester encoding is presented to transmit identification number from the Tag to the Reader. The novel identification system co...

The spectra of d3Δ–a3П (7, 1) band of CS radical were measured by optical heterodyne–concentration modulation spectroscopy in the region from 11 640 to 12 230 cm−1. In total, we assigned three hundred and four lines, of which Ree and Rff branches in the d3Δ1–a3П0 subsystem and more than a hundred lines were first observed and identified. The anomal...

The CS radical was generated by discharging the mixture gas of CS2 and Helium. The Doppler limited spectra of CS were recorded in the region of 12350-12950 cm-1 using optical heterodyne concentration modulation absorption spectroscopy. Three hundred and twenty-six lines were recorded and assigned to the d3Δ-a3Π (8,1) band, in which eighty-three tra...

Rotationally resolved absorption spectra of I2+ were recorded in 12 065–13 062 cm−1 region by employing optical heterodyne velocity modulation absorption spectroscopy. In total, 4054 lines were assigned to 24 bands in the A2Π3/2,u–X2Π3/2,g system spanning the vibrational levels υ′′ = 1−4 and υn′ = 11−19. The assigned lines were globally fitted and...

The Doppler-limited absorption spectrum of the O2+18 cation was observed using a Ti–Sapphire laser system (in region of 12 060–12 800 cm−1) by optical heterodyne velocity modulation absorption spectroscopy. Precise molecular constants (BυBυ, DυDυ, pυpυ, qυqυ, γυγυ) were obtained for the involved levels by fitting spectral lines of (3, 20) and (4, 2...

The rotationally resolved spectra of the c3Πu–b3Πg system of P2 in the 16620–17860 cm−1 region is reanalyzed here to obtain more assignments of the rotational lines and more accurate molecular constants. Approximately 500 spectral lines were assigned to six subbands: the Ω=0, 1 and 2 components of the (2, 3) band, the Ω=0 and 2 components of the (1...

The predissociation of the v = 9 level in the b3Pig state by the c3Sigmag+ state of helium eximer (He2) was studied based on the newly observed (9, 3) band in the b3Pig-a3Sigmau+ system in the region of 12065-12445 cm-1 employing optical heterodyne-concentration modulation absorption spectroscopy. With the help of the previous potential energy curv...