Abstract

The recently developed dual-wavelength thermal lens spectrometer, which is capable of simultaneously measuring thermal lens signals at two different wavelengths, has been used to simultaneously determine two component samples and solution pHs. Compared to conventional absorption spectrophotometry, this dual-wavelength technique offers advantages that include fast data acquisition and higher sensitivity. With the use of 20-mW excitation beams, the limits of detection for the simultaneous determination of ferroin and iron(II) bipyridyl complexes mixtures are estimated to be 3.6 × 10⁻⁹ M and 8.4 × 10⁻⁹ M, respectively. In addition, the high monochromaticity of the laser makes this technique uniquely suited for the simultaneous determination of two-component samples whose absorption bandwidths are too narrow to be determined by the conventional spectrophotometric method. The limits of detection for the Er³⁺ and Nd³⁺ ions in the two-component mixtures are estimated to be 8.9 × 10⁻⁴ M and 7.6 × 10⁻⁵ M, respectively. Solution pHs have also been sensitively and accurately determined by using this technique to measure the concentrations of the protonated and deprotonated forms of an indicator. Similar to the two-component sample determination, this thermal lens technique is superior to the conventional spectrophotometric method because it is fast, has relatively higher sensitivity, and allows an indicator to be used over a wider pH range. Solution pHs, ranging from 2 to 9, have been determined accurately with this technique, with the use of such indicators as phenol red, methyl orange, and thymol blue, whose concentrations can be as low as 10⁻⁹ M.

Current-induced thermal-lens spectrometry

Pavel A. Gorkin, Mikhail A. Proskurnin, Boris K. Zuev, Andrei A. Zhirkov, and Vladimir V. Yagov
Opt. Lett. 34(5) 680-682 (2009)

Near-infrared thermal lens spectrometer based on an erbium-doped fiber amplifier and an acousto-optic tunable filter, and its application in the determination of nucleotides

Mauricio S. Baptista and Chieu D. Tran
Appl. Opt. 36(27) 7059-7065 (1997)

Laser induced thermal lens microscopy for highly sensitive determination of captopril

Nader Shokoufi, Atefeh Abbasi-Ahd, and Kazem Kargosha
Appl. Opt. 56(11) E58-E63 (2017)

Two-photon-absorption-induced accumulated thermal effect on femtosecond Z-scan experiments studied with time-resolved thermal-lens spectrometry and its simulation

Kenji Kamada, Kinu Matsunaga, Akihiro Yoshino, and Koji Ohta
J. Opt. Soc. Am. B 20(3) 529-537 (2003)

Modeling the population lens effect in thermal lens spectrometry

J. R. Silva, L. C. Malacarne, M. L. Baesso, S. M. Lima, L. H. C. Andrade, C. Jacinto, M. P. Hehlen, and N. G. C. Astrath
Opt. Lett. 38(4) 422-424 (2013)