Vol. 38, issue 05, article # 7

Abstract:

This paper demonstrates for the first time the possibility of exciting anti-Stokes fluorescence of PO-fragments of organophosphates. Using the example of drop-liquid traces of triethyl phosphate on a paper surface, it was determined that the relative population of vibrational levels v´´ = 1 and v´´ = 2 corresponds to a vibrational temperature of fragments of about 780 K. Indicators of significant violation of the equilibrium distribution of fragments over rotational energy levels were revealed. It has been determined that the method of exciting anti-Stokes fluorescence of PO-fragments of triethyl phosphate from the first vibrational level of the ground state X²Π (v´´ = 1) to the zero vibrational level of the electronically excited state A²Σ⁺ (v´ = 0) provides the highest noise immunity of the LF/LIF method. The results can be used to select the optimal technique for exciting fluorescence of PO-fragments when implementing the LF/LIF method for remote detection of organophosphate traces.

Keywords:

organophosphate, trace, laser fragmentation, phosphorus oxide, PO-fragment, laser-induced fluorescence

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References:

1. Rodgers M.O., Asai K., Davis D.D. Photofragmentation-laser induced fluorescence: A new method for detecting atmospheric trace gases // Appl. Opt. 1980. V. 19, N 21. P. 3597–3605. DOI: 10.1364/AO.19.003597.
2. Bradshaw J., Davis D.D. Sequential two-photon-laser-induced fluorescence: A new method for detecting atmospheric trace levels of NO // Opt. Lett. 1982. V. 7, N 5. P. 224–226. DOI: 10.1364/OL.7.000224.
3. Bradshaw J., Rodgers M., Davis D. Single photon laser-induced fluorescence detection of NO and SO₂ for atmospheric conditions of composition and pressure // Appl. Opt. 1982. V. 21, N 14. P. 2493–2500. DOI: 10.1364/AO.21.002493.
4. Bradshaw J.D., Rodgers M.O., Sandholm S.T., Kesheng S., Davis D.D. A two-photon laser-induced fluorescence field instrument for ground-based and airborne measurements of atmospheric NO // J. Geophys. Res. 1985. V. 90, N D7. P. 12861–12873.
5. Arusi-Parpar T., Heflinger D., Lavi R. Photodissociation followed by laser-induced fluorescence at atmospheric pressure and 24 °C: A unique scheme for remote detection of explosives // J. Appl. Opt. 2001. V. 40, N 36. P. 6677–6681. DOI: 10.1364/AO.40.006677.
6. Bessler W., Schulz C., Lee T., Jeffries J., Hanson R. Strategies for laser-induced fluorescence detection of nitric oxide in high-pressure flames. I. A–X(0, 0) excitation // Appl. Opt. 2002. V. 41, N 18. P. 3547–3557. DOI: 10.1364/AO.41.003547.
7. Bessler W., Schulz C., Lee T., Jeffries J., Hanson R. Strategies for laser-induced fluorescence detection of nitric oxide in high-pressure flames. II. A–X(0, 1) excitation // Appl. Opt. 2003. V. 42, N 12. P. 2031–2042. DOI: 10.1364/AO.42.002031.
8. Arusi-Parpar T., Fastig S., Shapira J., Shwartzman B., Rubin D., Ben-Hamo Y., Englander A. Standoff detection of explosives in open environment using enhanced photodissociation fluorescence // Proc. SPIE. 2010. V. 7684. P. 76840L–7. DOI: 10.1117/12.850911.
9. Wynn C.M., Palmacci S., Kunz R.R., Rothschild M. Noncontact detection of homemade explosive constituents via photodissociation followed by laser-induced fluorescence // Opt. Express. 2010. V. 18, N 6. P. 5399–5406. DOI: 10.1364/OE.18.005399.
10. Wynn C.M., Palmacci S., Kunz R.R., Aernecke M. Noncontact optical detection of explosive particles via photodissociation followed by laser-induced fluorescence // Opt. Express. 2011. V. 19, N 19. P. 18671–18677. DOI: 10.1364/OE.19.018671.
11. Schulz C., Sick V., Heinze J., Stricker W. Laser-induced-fluorescence detection of nitric oxide in high-pressure flames with A–X(0, 2) excitation // Appl. Opt. 1997. V. 36, N 15. P. 3227–3232. DOI: 10.1364/AO.36.003227.
12. Bobrovnikov S.M., Gorlov E.V., Zharkov V.I., Safyanov A.D. Lazerno-indutsirovannaya fluorestsentsiya PO-fotofragmentov organofosfatov // Optika atmosf. i okeana. 2022. V. 35, N 8. P. 613–618. DOI: 10.15372/AOO20220803; Bobrovnikov S.M., Gorlov E.V., arkov V.I., Safyanov A.D. Laser-induced fluorescence of PO photofragments of organophosphates // Atmos. Ocean. Opt. 2022. V. 35, N 6. P. 639–644.
13. Daugey N., Shu J., Bar I., Rosenwaks S. Nitrobenzene detection by one-color laser photolysis/laser induced fluorescence of NO (v = 0–3) // Appl. Spectrosc. 1999. V. 53, N 1. P. 57–64. DOI: 10.1366/0003702991945227.
14. Shu J., Bar I., Rosenwaks S. Dinitrobenzene detection by use of one-color laser photolysis and laser-induced fluorescence of vibrationally excited NO // Appl. Opt. 1999. V. 38, N 21. P. 4705–4710. DOI: 10.1364/AO.38.004705.
15. Shu J., Bar I., Rosenwaks S. The use of rovibrationally excited NO photofragments as trace nitrocompounds indicators // Appl. Phys. B. 2000. V. 70, N 4. P. 621–625. DOI: 10.1007/s003400050870.
16. Castle K.J., Abbott J.E., Peng X., Kong W. Photodissociation of o-nitrotoluene between 220 and 250 nm in a uniform electric field // J. Phys. Chem. A. 2000. V. 104, N 45. P. 10419–10425. DOI: 10.1021/jp0009150.
17. Sausa R.C., Miziolek A.W., Long S.R. State distributions, quenching, and reaction of the phosphorus monoxide radical generated in excimer laser photofragmentation of dimethyl methylphosphonate // J. Phys. Chem. 1986. V. 90. P. 3994–3998. DOI: 10.1021/j100408a033.
18. Sankaranarayanan S. g-Centroids and Franck–Condon factors for the bands of A²Σ - X²Π system of PO molecule // Indian J. Phys. 1966. V. 40. P. 678.
19. Wong K.N., Anderson W.R., Kotlar A.J. Radiative processes following laser excitation of the A²Σ⁺ state of PO // J. Chem. Phys. 1986. V. 85, N 5. P. 2406–2413. DOI: 10.1063/1.451096.
20. Yin Y., Shi D., Sun J., Zhu Z. Transition probabilities of emissions and rotationless radiative lifetimes of vibrational levels for the PO radical // Astrophys. J. Suppl. Ser. 2018. V. 236, N 34. P. 1–15. DOI: 10.3847/1538-4365/aac16a.
21. Smyth K.C., Mallard W.G. Two-photon ionization processes of PO in a C₂H₂/air flame // J. Chem. Phys. 1982. V. 77, N 4. P. 1779–1787. DOI: 10.1063/1.444074.
22. Verma R.D., Dixit M.N., Jois S.S., Nagaraj S., Singhal S.R. Emission spectrum of the PO molecule. Part II. ²Σ - ²Σ transitions // Can. J. Phys. 1971. V. 49, N 24. P. 3180–3200. DOI: 10.1139/p71-379.
23. Bobrovnikov S.M., Gorlov E.V., Zharkov V.I. Effektivnost' lazernogo vozbuzhdeniya PO-fotofragmentov organofosfatov // Optika atmosf. i okeana. 2022. V. 35, N 3. P. 175–185. DOI: 10.15372/AOO20220301; Bobrovnikov S.M., Gorlov E.V., Zharkov V.I. Efficiency of laser excitation of PO photofragments of organophosphates // Atmos. Ocean. Opt. 2022. V. 35, N 4. P. 329–340.
24. Bobrovnikov S.M., Gorlov E.V., Zharkov V.I., Murashko S.N. Otsenka effektivnosti lazernogo vozbuzhdeniya perehoda B²Σ⁺ (vʹ = 0) - X²Π (v¢¢ = 0) oksida fosfora // Optika atmosf. i okeana. 2022. V. 35, N 5. P. 361–368. DOI: 10.15372/AOO20220503.
25. Sun Y., Shu Y., Xu T. Review of the photodecomposition of some important energetic materials // Cent. Eur. J. Energ. Mater. 2012. V. 9. P. 411–423.
26. Bobrovnikov S.M., Gorlov E.V., Zharkov V.I., Murashko S.N. Dvuhimpul'snaya lazernaya fragmentatsiya/lazerno-indutsirovannaya fluorestsentsiya sledov organofosfatov // Opt. zhurn. 2025. V. 92, N 2. P. 106–115. DOI: 10.17586/1023-5086-2025-92-02-106-115.
27. Bobrovnikov S.M., Gorlov E.V., Zharkov V.I., Zaitsev N.G. Sistema sinhronizatsii lazerov dlya dvuhimpul'snoi lazernoi diagnostiki // Optika atmosf. i okeana. 2025. V. 38, N 4. P. 302–307.