Fig. 2
From: Optical refrigeration on cadmium selenide/cadmium sulfide quantum dots
PL spectra of a sample with core radius \(\sim 3.3\) nm with 4 monolayers (ML) of CdS shell, at sub-band excitation: (a) Typical UCPL spectrum with \(\varepsilon _{\text {ex}}=1.946\) eV. (b) \(\eta _{\text {c}}(\varepsilon _{\text {ex}})\) from Eq. (4) with \(a_{\text {b}}/a=300\) ppm and \(\eta =0.998\).
