Signal convolution model and obtaining the response function for determination of fluorescence time

• Grant number: 19/10204-9
• Support Opportunities: Scholarships in Brazil - Scientific Initiation
• Start date: August 01, 2019
• End date: July 31, 2020
• Field of knowledge: Physical Sciences and Mathematics - Physics - Condensed Matter Physics
• Principal Investigator: Leonardo de Boni
• Grantee: Victor Antonio Siqueira Marques
• Host Institution: Instituto de Física de São Carlos (IFSC). Universidade de São Paulo (USP). São Carlos , SP, Brazil

Abstract

Obtaining the fluorescence lifetimes of organic or inorganic compounds by means of optical excitation is useful for describing photophysical and photochemical processes that can be applied in several areas. As an example, there are applications in photonics, chemistry, biology and medicine, since the fluorescence lifetime can show a lot about some properties of fluorophores. It can be emphasized that fluorescence life time behavior and its temporal decay constant can quantify the purity of a particular compound in diverse solutions (different solvents), distinguish distinct compounds in an unknown sample and show the existence and type of interactions between molecules, such as the formation of aggregates and photodegradation (mainly in organic molecules). Thus, the quantification of the described processes depends greatly on the extent of these fluorescence lifetimes and their dependences. However, although there are equipment to perform these measurements, because the fluorescence lifetimes of some compounds are very short, more precise analysis is required. In such cases, the response of the measuring equipment (detector, cables and oscilloscope) must be taken into account, due to its temporal responses, impedance and electrical capacitance. In this context, a programming routine based on the method and convolution of signals will be elaborated to obtain the pure response of the fluorescence life time. This routine aims to use the induced signal in the combined measurement system with mathematical functions of the exponential type to produce the fluorescence signal measured by the same system. Thus, a fluorescence lifetime is expected without the influence of the time response given by the metering system.