研究目的
To derive a practical formula describing the dependence of partially saturated ?uorescence on the exciting-laser power and to extend the range of exciting laser power to the region of partial saturation to enhance the signal-to-noise ratio.
研究成果
The intuitive relation (1) used in previous publications was found to be correct up to second order of Maclaurin expansion of the derived result. Comparing the performance of least squares ?tting of relation (1) and more rigorous relation (25) to the results of a 4-level model of ?uorescence revealed a practical suggestion to use relation (1) for the range of laser pulse energies EL limited by β EL ≤ 0.4. It was shown that measurements of laser induced plasma ?uorescence can be invasive, especially if laser radiation can hit a solid surface and increase the discharge intensity or if laser intensity is high enough to in?uence plasma chemistry by photodissociation.
研究不足
The practical formula F (EL) = α EL / (1 + β EL) is reliable up to dF/dEL ≈ 0.5 α, where the deviation from the right value is less then 20%. This corresponds to the values β EL of ca. 0.4. The 2-parameter approximation is thus quite reliable if the values of EL included in the ?t are limited to β EL ≤ 0.4.
1：Experimental Design and Method Selection:
A four-level model was implemented to test the theory derived, suitable for a diatomic molecule excited from ground vibronic state to excited electronic state with v' =
2：Sample Selection and Data Sources:
The model was particularly suitable for a diatomic molecule excited from ground vibronic state to excited electronic state with v' = 0, i.e., for moderate temperatures (< 1000 K).
3：List of Experimental Equipment and Materials:
The laser set-up consisted of pumping Nd:YAG laser (Spectra-Physics, Quanta-Ray PRO-270-30), dye laser (Sirah, Precision Scan) and a doubling crystal unit. Fluorescence radiation was detected by an ICCD camera (Princeton instruments, PI-MAX 1024RB-25-FG-43).
4：3). Experimental Procedures and Operational Workflow:
4. Experimental Procedures and Operational Workflow: The temporal shape of the laser was simulated by the function I(t) = a t^b e^{-c t}, with the parameters b =
5：6 and c = 44 ns^{-1}. The time-integrated ?uorescence was calculated from the 4-level model for a range of laser-power values EL and a least squares ?t of equations (1) or (25) was performed. Data Analysis Methods:
The results were compared by least squares ?tting of equations (1) and (25) to the results of a 4-level model of ?uorescence.
独家科研数据包，助您复现前沿成果，加速创新突破
获取完整内容
