Focus The third dye laser also shifts the green light to orange, frequency-dou bles the orange light, and mixes the resulting 331.0-nm radiation with the 1064.0-nm line from the Nd:YAG la ser, yielding a 252.5-nm line. Radia tion from the second and third dye la sers forms the input to a Xe-Ar fre quency mixer, which generates vacuum-UV radiation (116.5 nm) that is used for the first Kr-81 transition. Zare pointed out that there is a les son to be learned from a scheme such as this, which includes the use of four lasers, two frequency doublers, a hy drogen Raman cell, and two mixers: "Often people think, 'Well, let those researchers have one laser if that's what they're interested in.' And they can't understand why we would want more than one laser. But the fact is that you can't do some of the things I've been talking about unless you're going to invest in them." In the past, many analytical chemis try techniques have emerged from pri or developments in physics. That is why the smart money is betting that analytical chemists will also be able to benefit from X-ray lasers, should they be successfully developed. According to Fred E. Lytle of Purdue University,
Nd: YAG laser
1064.0 nm (72 mj/pulse)
1064.0 nm x2
532.0 nm (green) 532.0 nm (green)
558.1 nm (2 mj/pulse)
Dye laser 1
J 532.0 nm (green)
Dye laser 2
669.0 nm (orange)
H2 Raman cell
1507.3 nm il»
Mixer
252.5 nm
1507.3 nm 252.5 nm
Xe-Ar cell
116.5 nm (ca. 500 nJ/pulse)
Figure 3. Generation of three beams at 116.5, 558.1, and 1064.0 nm
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