title: The effect of quantum size confinement on the optical properties of PbSe nanocrystals under exposure to heat and hydrostatic pressure.
abstract: A study based on photoluminescence and absorption measurements as a function of temperature and pressure for PbSe nanocrystals with sizes in the range 3-13 nm reveals the influence of size quantum confinement on the observed variation. In the case of the temperature variation, the effective bandgap changes from showing a positive rate of change to showing a negative one (for a quantum dot 3 nm in diameter), which can be accounted for by incorporating a linear variation of the carrier effective masses into a simple calculation of the exciton ground state in the quantum dot. In the case of the pressure variation, we observe a clear inverse correlation between the absolute value of the pressure coefficient and the nanocrystal size, a signature of quantum size confinement, with values changing from -76 to -41 meV GPa⁻¹ for quantum dots ranging from 13 to 3 nm in diameter, respectively, clearly smaller in absolute value than the rate for bulk PbSe (-84 meV GPa⁻¹). We used again the hypothesis of a linear variation of the carrier effective masses with pressure in order to fit this experimental variation quantitatively.
authors.affiliation: Instituto de Ciencia de los Materiales, Universidad de Valencia, PO Box 22085, E-46071 Valencia, Spain.
authors.forename: Esteban
authors.initials: E
authors.lastname: Pedrueza
authors.forename: Alfredo
authors.initials: A
authors.lastname: Segura
authors.forename: Rafael
authors.initials: R
authors.lastname: Abargues
authors.forename: Jose Bosch
authors.initials: JB
authors.lastname: Bailach
authors.forename: Jean Claude
authors.initials: JC
authors.lastname: Chervin
authors.forename: Juan P
authors.initials: JP
authors.lastname: Martínez-Pastor