Study On The Related Problems In The Analysis Of Trace Elements By Four Wave Mixing Spectroscopy

Trace elements have been made great achievements in many areas such as archaeology, health care, environment studies, cultural relics and so on. With the wider and deeper applications of these areas, higher precision of trace element analysis will be the future trend of research. To set up a convenient, reliable and low-cost method has become a major issue in trace element analysis. In this paper, trace element analyses are measured by degenerate four-wave mixing (DFWM) spectrometry. Firstly, matrix effects, resolution and atomic coherent effect are investigated in experiment and theory. Then, Based on the preliminary works, trace rubidium (Rb) analysis are investigated DFWM spectrometry in bittern samples. Main efforts are listed as follows:We analyzed Li element in Li2CO3 atomized in a graphite furnace using DFWM method. The effects of main factors such as acid anions, major metallic elements and chlorides on Li DFWM signal intensity are studied. It is found that NO3-, Mg, Ba, Sr and Na have no effects on Li DFWM signal. K, Cs and Ni enhance the Li DFWM signal, while SO42-, PO43-, Cl- and Ca cause serious depression. Finally, we used H3BO3 to eliminate the interference of chloride matrix. This work is of significance in trace other alkali metal analysis of real sample with DFWM. The investigation provides valuable information in enhancing DFWM signal and reducing the detection limit.Degenerate four-wave mixing (DFWM) is employed to detect rubidium (Rb) in a graphite furnace atomizer for trace elemental analysis. Firstly, the detect limit expression of DFWM was deduced in theory. Then detect limit of Rb was calculated as 7.02051 fg/mL. Based on the preliminary study, CsNO3 are taken as the matrix modifiers to lower the detection limit. With CsNO3, we reduce the detection limit from 7.02051 ng/mL to 0.90479 ng/mL. This investigation indicates the potential of DFWM in trace element analysis. Additionally, we used CswNO3 and HNO3 to eliminate the matrix effect in bittern samples. And the Rb content and Rb isotope abundance ratio in bittern samples were measured to be 29.715±0.003 mg·L4 and 2.449±0.001 respectively, which is very close to the ICP-MS value. It is indicated that the feasibility of DFWM with matrix modifiers in trace elemental analysis in bittern samples. In a degenerate two-level system of Rb atoms, DFWM was realized with electromagnetically induced transparency (EIT) and coherent population trapping (CPT) under the condition of four wave vectors do not match in vacuum. The phase compensation mechanism induced by anomalous dispersion was explained the experimental results successfully. Additional, the dependences of DFWM efficiency on the angle between the coupling and probe lights and on atomic density were studied. This work gives people new thought in understanding the mechanism of DFWM.