Spatially Resolved Temperature Determination of an Air/Acetylene Flame Using the Two-Step Laser-Enhanced Ionization Technique

Abstract

We have demonstrated a two-step laser-enhanced ionization (LEI) technique to be potentially useful in measuring a spatially resolved temperature in an atmospheric air/acetylene flame. As a complement to the existing optical methods, LEI detection shares the advantages of extremely high sensitivity and the capability of achieving a high spatial resolution, confined to the dual-beam intersection area of 1 mm × 1 mm. A theoretical model was developed to precisely extract the temperature information from the obtained two-step LEI signal. The physical parameters required in the experiment include simply the relative values of the LEI signals, associated with the fine-structure doublets of a selected thermometric species, and their corresponding laser energies. The subsequent treatment is also convenient without the need to know the absolute energy of the incident laser beam and to accurately calibrate the detection system. Al and Ga were selected as the thermometric species. The resultant radial and axial temperature mappings are consistent with each other and are also comparable with those reported by other optical methods.

Laser-Enhanced Ionization Detection of Pb in Seawater by Flow Injection Analysis with On-Line Preconcentration and Separation

“…The fuel C 2 H 2 and air were regulated at flow rates of 0.5 and 12.5 L/min, respectively, and were premixed prior to reaching the burner head. The corresponding flame temperature was measured as ∼2500 K. 32,33 Laser Radiation. Two tunable dye lasers (Spectra-Physics PDL-2A and PDL3), each pumped by individual Nd:YAG lasers (Spectra-Physics, DCR-2A and GCR3) in a second harmonic generator, were used as radiation sources.…”

Development of a novel spectrometric-based temperature probe and the investigation of atomic cloud generation in a tungsten coil atomizer

“…The difficulty to accurately determine gas phase temperatures in hard-to-reach places inside equipments is an important obstacle to a better understanding of physical-chemical processes occurring during atomic spectrometric determinations. Despite some effort 16,22 to present a simple, fast, effective alternative to the traditional Sn two-line method, 21 some work is required to develop a portable thermometer capable of reliable spatial-and time-resolved measurements. Using a handheld spectrometer, a fiber optic and a laptop computer, a novel temperature probe based on atomic emission spectrometry and the Boltzmann distribution equation is presented.…”

Application of Laser‐Enhanced Ionization Spectroscopy: Effect of Dissociation Constant on the Atomization Efficiency Determination in an Acetylene‐Air Flame

“…where n a is the free atom num ber den sity of an el e ment present in the flame, and nt is the to tal num ber den sity of the same el e ment ac tu ally nebulized. The lat ter can be ex plic itly expressed as 25 (2) where C is the con cen tra tion of the analyte so lu tion; the uptake (nebulization) rate (mL/min); the sam ple in tro duc tion ef fi ciency; f the flow rate (mL/s) of un burnt gases at room tem per a ture (298 K) and at mo spheric pres sure; n 298 the number of moles of spe cies at room tem per a ture; and nT the number of moles of com bus tion prod ucts at tem per a ture T. The value of n T /n 298 was pre vi ously de ter mined to be 1.0 for our case with an acet y lene/air ra tio of 1:25 and a flame tem per ature of 2500 K. 28,29 There fore, sub sti tut ing the ex per i men tal con di tions and the mea sured val ues into eq. 2 may give rise to the es ti mate of nt for dif fer ent al kali salts.…”

“…The fuel C 2 H 2 and air with flow rates of 0.5 L/min and 13 L/min, re spec tively, were pre mixed prior to reach ing the burner head. The cor re spond ing flame tem per a ture was de ter mined to be about 2500 K. 28,29 The up take rate into the burner head was held at 4.5 mL/min for all the aque ous so lutions of the ha lide com pounds.…”