Table 3. Literature data for the two-photon cross section of Rhodamine 6G in methanol or ethanol in the 1,054-1,064 nm region.

Most of the values (column no. 7) group around 10 GM. The average of all 11 measurements provides σ₂ = 12 ± 2 GM (average ± SE of mean). The underlined values are obtained either with mode-locked lasers or using the methods where the uncertainty in the second-order time correlation function of laser intensity g⁽²⁾ was removed. Out of these six measurements, the lowest (4.2 GM) (Kaatz and Shelton, 1999), was obtained by using Hyper Rayleigh scattering technique to calibrate the laser properties, including g⁽²⁾. The authors found that this method gave underestimated values of σ₂, compared to those obtained with standard calibration against one-photon fluorescence. Therefore, the suggested value of σ₂ is calculated by excluding this measurement and averaging the numbers selected in italic in column 7.

Wavelength (nm)	Solvent	Conc. (M)	Pulse	Original σ2 (GM)	Correction 1 σ2 (GM)	Correction 2 σ2 (GM) (final)	Ref.
1060	C2H5OH	n/a	ns	12.9 ± 6	25.8 ± 12a	10.1 ± 4.7 b	Hermann and Ducuing, 1972
1060	C2H5OH	10-3	60 ns	5.5	11a	5.5c	Bradley et al., 1972
1060	C2H5OH	10-4	30 ns	26	52a	26c	Vsevolodov et al, 1973
1060	C2H5OH	10-3	ps	3.6	7.2a	7.2	Bradley et al., 1972
1060	C2H5OH	10-6	110 ns	11 ± 5	22 ± 10a	11 ± 5c	Li and She, 1982
1064	C2H5OH	10-2	cw	12 ± 2	48 ± 8d	24 ± 4c	Catalano and Cingolani, 1982
1054	CH3OH	0.2	5 ps	10 ± 1	-	10 ± 1	Penzkofer and Leupacher, 1987
1064	CH3OD	2.2 10-6	125 ns	4.2 ± 0.8	-	4.2 ± 0.8	Kaatz and Shelton, 1999
1064	C2H5OH	10-4	10 ns	15 ± 1	30 ± 2a	15 ± 1c	Rodriguez, et al, 2007
1060	CH3OH	8 10-6	100 fs	10 ± 1	-	10 ± 2	Makarov et al., 2008
1060	CH3OH	n/a	100 fs	11 ± 1	-	11 ± 1	de Reguardati et al., 2016
Suggested conditions and cross section value
1060	CH3OH	10-5	100 fs			10 ± 1