Abstract

A novel technique applicable to remote sensing has been developed for determination of the chemical composition of microdroplets. Enhancement of stimulated anti-Stokes–Raman scattering (SARS) by external seeding of stimulated Raman scattering (SRS) at the Stokes shift lowers the detection limit of the minority species in multicomponent microdroplets. The technique is most useful in the investigation of microdroplets that contain fluorophores that can obscure the SRS signal. The SARS signal is to the blue of the pump laser and out of the fluorescence region of the fluorophore. Information about majority and minority species in multicomponent microdroplets can be determined from the enhanced SARS signals.

© 1999 Optical Society of America

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References

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    [CrossRef]
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1996 (2)

1995 (1)

M. M. Mazumder, K. Schaschek, R. K. Chang, J. B. Gillespie, “Efficient pumping of minority species stimulated Raman scattering by majority species SRS in a microdroplet of a binary mixture,” Chem. Phys. Lett. 239, 361–368 (1995).
[CrossRef]

1992 (2)

1990 (1)

1985 (1)

Acker, W. P.

Armstrong, R. L.

Biswas, A.

Chang, R. K.

Eckbreth, A. C.

A. C. Eckbreth, Laser Diagnostics for Combustion Temperature and Species (Abacus, Tunbridge Wells, U.K., 1988).

Fields, M. H.

Fleming, J. W.

Gillespie, J. B.

M. M. Mazumder, K. Schaschek, R. K. Chang, J. B. Gillespie, “Efficient pumping of minority species stimulated Raman scattering by majority species SRS in a microdroplet of a binary mixture,” Chem. Phys. Lett. 239, 361–368 (1995).
[CrossRef]

Kwok, A. S.

Leach, D. H.

Mazumder, M. M.

M. M. Mazumder, K. Schaschek, R. K. Chang, J. B. Gillespie, “Efficient pumping of minority species stimulated Raman scattering by majority species SRS in a microdroplet of a binary mixture,” Chem. Phys. Lett. 239, 361–368 (1995).
[CrossRef]

Owrutsky, J. C.

Pasternack, L.

Pinnick, R. G.

Popp, J.

Qian, S.-X.

Schaschek, K.

M. M. Mazumder, K. Schaschek, R. K. Chang, J. B. Gillespie, “Efficient pumping of minority species stimulated Raman scattering by majority species SRS in a microdroplet of a binary mixture,” Chem. Phys. Lett. 239, 361–368 (1995).
[CrossRef]

Snow, J. B.

Chem. Phys. Lett. (1)

M. M. Mazumder, K. Schaschek, R. K. Chang, J. B. Gillespie, “Efficient pumping of minority species stimulated Raman scattering by majority species SRS in a microdroplet of a binary mixture,” Chem. Phys. Lett. 239, 361–368 (1995).
[CrossRef]

J. Opt. Soc. Am. B (1)

Opt. Lett. (5)

Other (1)

A. C. Eckbreth, Laser Diagnostics for Combustion Temperature and Species (Abacus, Tunbridge Wells, U.K., 1988).

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Figures (4)

Fig. 1
Fig. 1

Pump-only SARS spectra from ∼25-µm-radius cyclohexane microdroplets. The horizontal axis indicates the wave-number shift in inverse centimeters from the 532-nm pump laser. Only the higher-gain Raman modes achieve SRS threshold and generate a SARS signal.

Fig. 2
Fig. 2

Pump-only (solid curves, offset for clarity) and pump-seed (dashed curves) SARS spectra from ∼25-µm-radius cyclohexane microdroplets. The labels indicate the wave-number shift of the SARS peak corresponding to a seeded SRS mode.

Fig. 3
Fig. 3

Pump-only (solid curves) and pump–seed (dashed curves) SARS spectra of multicomponent mixture droplets consisting of 15% chloroform, 85% ethanol, and 5% toluene in the spectral range between -625 and -1025 cm-1. Seeding of SRS enhances SARS from the weaker-gain modes of (a) chloroform at -667 cm-1, (b) ethanol at -884 cm-1, (c) toluene at -1004 cm-1.

Fig. 4
Fig. 4

(a) Pump-only fluorescence–lasing spectra of microdroplets consisting of 5% toluene and 10-5 M R6G in ethanol. The toluene SRS at 1004 cm-1 is not distinguishable from the lasing modes. (b) Pump–seed SARS spectrum of the same microdroplets. No SARS signal was detected without seeding.

Equations (1)

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CgSRSIhotspotLgain=ΓleakLleak=2πnλQ Lleak,

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