Laser-induced fluorescence measurements on CdSe quantum dots

Abstract

In this paper, we report on photoluminescence decay measurements on CdSe quantum dots (QDs) as a function of size in the diameter range of 2.1 to 3.5 nm. The nanoparticles were synthesized by the kinetic growth method from CdO and elemental Se precursors. We studied the effects of growth time on the diameter, emission spectrum and the fluorescence lifetime of the synthesized QDs. The decay time measurements were performed using single shot time-resolved laser-induced fluorescence techniques using a Nd:YAG laser system. Two different decay times were measured on each CdSe sample, a fast one and a relatively slow one. The slow decay was found to be size dependent whereas the fast one was independent of the QD diameter. .

Bright and Uniform Green Light Emitting InP/ZnSe/ZnS Quantum Dots for Wide Color Gamut Displays

“…In Figure S6, the PL decay profiles, dependent on the probe wavelength, were measured at 10 nm spectral intervals for all QDs. The PL decay curves were fitted with triexponential functions: a fast component (τ 1 = 3–4 ns) attributed to the intrinsic charge transfer processes between the neutral (core) and surface trap (charged) states, an intermediate component (τ 2 = 30–40 ns) due to the intrinsic recombination of initially populated neutral states, and a long-lived component (τ 3 > 100 ns) from the trap state emissions. − On the basis of the PL decay curves, which were analyzed by global fitting to obtain the kinetic time constants and respective amplitudes, we reconstructed the time-resolved PL spectra (TRPS) and the corresponding DAS that are shown in Figure . In the TRPS (Figure a–c), the red-shifted peak maximum represents the emission at longer wavelengths in the PL spectra, which is attributable to the long-lived component.…”

Photoinduced interaction of CdSe quantum dot with coumarins

“…The larger the value of A 2 (related to the longer-lifetime component), the better the surface condition (fewer the surface defects), and the larger the role of surface-related emission is [32]. The observed value of longer lifetime amplitude A 2 ¼0.45 is significantly higher than that reported in the literature 0.2870.12 [33]. This relatively larger share of the longer lifetime component is a clear indication of major surface-related emission caused by the radiative recombination of charge carriers involving surface states.…”

Optoelectronic module for quantification of biomarkers based on fluorescence

“…There is a direct relationship between the wavelength of the emitted light and the electron energy change [2,3,4]. A particularly useful example is those when in a QD there is an electron energy state with n = 1 and it returns into an atom where E = 0, so that:…”

“…In order to determine the intensity of the light emitted by the source that is necessary to obtain the phenomenon of fluorescence of QDs, we use Beer's law [2,3]. Suppose that we have a diluted solution which absorbes the light having an initial intensity I.…”

“…For this purpose the equipment must ensure the absorption of light and the detection of QDs emitted light. Thus, for measuring the lifetime of fluorescence it is recommended to use a laser with a short pulse of light which will excite the sample, and subsequent emission of fluorescence will be recorded as a function of time [3].…”