Enhancement of the Anti-Stokes Fluorescence of Hollow Spherical Carbon Nitride Nanostructures by High Intensity Green Laser

Pavel V Zinin,Anupam K Misra,Shiv K Sharma,Tayro E Acosta-Maeda

doi:10.3390/nano11102529

Abstract

Fluorescence spectra of graphitic (g-C3N4) and spherical (s-C3N4) modifications of carbon nitride were measured as a function of green pulsed (6 ns-pulse) laser intensity. It was found that the intensity of the laser increases the maximum of the fluorescence shifts towards the anti-Stokes side of the fluorescence for s-C3N4 spherical nanoparticles. This phenomenon was not observed for g-C3N4 particles. The maximum of the anti-Stokes fluorescence in s-C3N4 nanoparticles was observed at 480 nm. The ratio of the intensity of the anti-Stokes peak (centered at 480 nm) to that of the Stokes peak (centered at 582 nm) was measured to be I484/582 = 6.4 × 10−3 at a low level of intensity (5 mW) of a green pulsed laser, whereas it rose to I484/582 = 2.27 with a high level of laser intensity (1500 mW).

Highlights

High Intensity Green Laser.Recently, graphite-like carbon nitrides have begun to attract attention because of their possible use in tasks such as splitting water by optical methods [1], as metal-free catalysts [2], and for the degradation of organic pollutants in water under the influence of visible light [3]
In Ref. [8], it was found that the intensity of the fluorescence excited in s-C3 N4 is more than three orders higher than that for g-C3 N4 modification
This paper looks at the non-linear effect of the pulsed laser excitation with different graphitic C3 N4 structures including s-C3 N4 and disordered g-C3 N4 modifications on anti-Stokes fluorescence

Summary

Introduction

High Intensity Green Laser.Recently, graphite-like carbon nitrides have begun to attract attention because of their possible use in tasks such as splitting water by optical methods [1], as metal-free catalysts [2], and for the degradation of organic pollutants in water under the influence of visible light [3]. The high yield of fluorescence, small size, intrinsic optical properties, low toxicity, and useful non-covalent interactions make graphitic carbon nitride nanoparticles an effective optical sensor to detect various ions [6]. They can be used as a traceable and pH-responsive drug delivery system [7]. The non-linear behavior of the anti-Stokes fluorescence in graphitic carbon nitride has not been investigated. This paper looks at the non-linear effect of the pulsed laser excitation with different graphitic C3 N4 structures including s-C3 N4 and disordered g-C3 N4 modifications on anti-Stokes fluorescence. Single-layered g-C3 N4 quantum dots have previously been used for two-photon fluorescence imaging of cellular nucleus [14,15]

Methods

Results

Discussion

Conclusion