Ch2 : 635 - 697. W Plan-Apochromat 20x/1.0 DIC M27 75mm. Exposed with 50ppm CdTe in Embryo Media at 6hpf. Imaged at 5dpf in agarose. A – Excitation: 405nm B – Excitation: 800nm CdTe quantum dots with excitation wavelength of 400nm and emission peak of 645 are visible inside the intestinal track of a 5dpf zebrafish embryo. Both images are taken with a Zeiss 710 NLO at PNNL/EMSL with “A” in single photon mode (405nm) and “B” in 2-photon mode (800nm). Single photon images provide a brighter image but 2-photon images provide a clearer (more focused) image.