scholarly journals Selective two-photon absorption in carbon dots: a piece of the photoluminescence emission puzzle

Nanoscale ◽  
2018 ◽  
Vol 10 (26) ◽  
pp. 12505-12514 ◽  
Author(s):  
Carla I. M. Santos ◽  
Inês F. A. Mariz ◽  
Sandra N. Pinto ◽  
Gil Gonçalves ◽  
Igor Bdikin ◽  
...  
Keyword(s):  
Total Energy ◽  
Carbon Dots ◽  
Emission Spectra ◽  
Photon Absorption ◽  
Carbon Nanodots ◽  
Nonlinear Excitation ◽  
Excitation Mode ◽  
Two Photon Absorption ◽  
Two Photon ◽  
Linear And Nonlinear

Optical spectroscopy of carbon nanodots reveals excitation-mode-dependent emission. Linear and nonlinear excitation at the same total energy results in different emission spectra.

scholarly journals Photolysis of SiH4 by the Third Harmonic of a Nd:YAG Laser at 355 NM

1996 ◽  
Vol 16 (4) ◽  
pp. 245-253
Author(s):  
K. Sentrayan ◽  
E. Haque ◽  
A. Michael ◽  
V. S. Kushawaha
Keyword(s):  
Laser Energy ◽  
Emission Spectra ◽  
Photon Absorption ◽  
Absorption Process ◽  
Third Harmonic ◽  
Two Photon Absorption ◽  
Two Photon ◽  
The Third ◽  
Atomic Lines ◽  
White Deposit

The photolysis of silane (SiH4) was carried out using the third harmonic of a Nd: YAG laser at 355 nm, at a fixed SiH4 pressure of 350 Torr, varying the laser energy fluence in the range of 30–300 Jcm-2. The emission spectra indicates that the photofragments formed are SiH2, SiH, Si, H2, and H. The (A1B1-X1A1) transitions at 552.7 nm, 525.3 nm, 505.6 nm, and 484.7 nm of SiH2 are due to a two photon absorption process. The (A2Δ-X2π) transitions of SiH at 425.9 nm, 418 nm, 414.2 nm, 412.8 nm and 395.6 nm are due to a three photon absorption process. The brownish white deposit on the cell windows indicates the presence of amorphous silicon (a:Si-H). The two atomic lines of Si(4s1P0→ 3p21D2) at 288.1 nm, and (4s3Pj→ 3P3Pj) at 251.6 nm are observed. The atomic Si transitions are due to a three photon absorption. We observed seven transitions due to molecular hydrogen at wavelengths 577.5 nm, 565.5 nm, 534.4 nm, 542.5 nm, 471 nm, 461.7 nm, and 455.4 nm. These bands are due to a four photon absorption proc6ss. In addition to the molecular bands we also observed hydrogen atomic lines Hβ, Hγ and Hδ.

Preparation and Photophysical Properties of All-trans Acceptor–π-Donor (Acceptor) Compounds Possessing Obvious Solvatochromic Effects

2017 ◽  
Vol 70 (9) ◽  
pp. 1048
Author(s):  
Yu-Lu Pan ◽  
Zhi-Bin Cai ◽  
Li Bai ◽  
Sheng-Li Li ◽  
Yu-Peng Tian
Keyword(s):  
Density Functional Theory ◽  
Density Functional ◽  
Photophysical Properties ◽  
Emission Spectra ◽  
Photon Absorption ◽  
Linear Absorption ◽  
Functional Theory ◽  
Two Photon Absorption ◽  
Two Photon ◽  
Donor Acceptor

A series of all-trans acceptor–π-donor (acceptor) compounds (BAQ, SFQ, BLQ, and XJQ) were conveniently synthesised and characterised by infrared, nuclear magnetic resonance, mass spectrometry, and elemental analysis. Their photophysical properties, including linear absorption, one-photon excited fluorescence, two-photon absorption, and two-photon excited fluorescence, were systematically investigated. All the compounds show obvious solvatochromic effects, such as significant bathochromic shifts of the emission spectra and larger Stokes shifts in more polar solvents. Under excitation from a femtosecond Ti : sapphire laser with a pulse width of 140 fs, they all exhibit strong two-photon excited fluorescence, and the two-photon absorption cross-sections in THF are 851 (BAQ), 216 (SFQ), 561 (BLQ), and 447 (XJQ) GM respectively. A combination of density functional theory (DFT) and time-dependent density functional theory (TDDFT) approaches was used to investigate the relationships between the structures and the photophysical properties of these compounds. The results show that they may have a potential application as polarity-sensitive two-photon fluorescent probes.

scholarly journals Supramolecular Bodipy Dye Architectures for Advanced Light Harvesting and Energy Transfer Applications

2021 ◽  
Author(s):  
Muhammad Yousaf
Keyword(s):  
Light Harvesting ◽  
Dye Sensitized Solar Cells ◽  
Fluorescence Emission ◽  
Emission Spectra ◽  
Photon Absorption ◽  
Quantum Yields ◽  
Reaction Centre ◽  
Two Photon Absorption ◽  
Two Photon ◽  
Sensitized Solar Cells

Shape-persistent phenylacetylene macrocycles have been explored in a number of optoelectronic and light-harvesting applications, including two-photon absorption. Likewise, BODIPY (4,4-difluoro-4-bora-3a,4a-diaza-s-indacenes) dyes have also been extensively used in material applications, owing to their tunable, intense absorption and sharp emission spectra exhibiting high quantum yields. Combining these two architectures, this thesis presents a derivative where a BODIPY is contained orthogonally within the phenylacetylene-macrocycle. This structure was inspired by photosystem II antennae complexes where energy is obsorbed by antennae complexes and funneled down to a reaction centre. Specifically, this family of molecules uses the phenylacetylene macrocycle to harvest the light and transfer it to the BODIPY core, and this has been observed by examining the fluorescence emission from the BODIPY (Figure 1). This novel dye design if coupled to a donor (D) and acceptor (A) capable of anchoring to TiO2 could be modified to become a π-spacer (i.e. D-π-A motif) for dye-sensitized solar cells resulting in panchromatic absorption, and ultimately more efficient devices.

scholarly journals Linear and nonlinear luminescence properties of thiophene based materials

2005 ◽  
Vol 70 (2) ◽  
pp. 201-208 ◽  
Author(s):  
L.U. Ping ◽  
Ming Xia
Keyword(s):  
Cross Sections ◽  
Single Photon ◽  
Photon Absorption ◽  
Luminescence Properties ◽  
Quantum Yields ◽  
Two Photon Absorption ◽  
Two Photon ◽  
Fs Laser ◽  
Thiophene Derivatives ◽  
Linear And Nonlinear

Three new thiophene based organic luminescence compounds, i.e., 2,5-bis(4?-N,N-dimethylaminostyryl) thiophene (BMST), 2,5-bis(4?-N,N-diethylaminostyryl)thiophene (BEST) and 2,5-bis(4?-N-cyclobutylaminostyryl)thiophene (BBST), were synthesized. All of their measured single-photon excited fluorescence (SPEF) are located in the range of ? 530 nm with quantum yields of around 40 %, and the corresponding lifetime was ? 1 ns. The examined compounds show strong solvatochromism in their SPEF spectra. Excited by a fs laser at 800 nm, a strong up-converted fluorescence of the examined compounds was detected. The profile of two-proton excited fluorescence (TPEF) was similar to that of SPEF. The two-photon absorption (TPA) cross sections of the compounds were determined by the TPEF method. All the compounds showed large TPA cross sections. Hence these thiophene derivatives may have good TPA properties.

2,5-Bis(azulenyl)pyrrolo[3,2-b]pyrroles – the key influence of the linkage position on the linear and nonlinear optical properties

2017 ◽  
Vol 5 (10) ◽  
pp. 2620-2628 ◽  
Author(s):  
Yevgen M. Poronik ◽  
Leszek M. Mazur ◽  
Marek Samoć ◽  
Denis Jacquemin ◽  
Daniel T. Gryko
Keyword(s):  
Optical Properties ◽  
Absorption Spectrum ◽  
Nonlinear Optical ◽  
Photon Absorption ◽  
No Emission ◽  
Visible Light Absorption ◽  
Two Photon Absorption ◽  
Two Photon ◽  
Linkage Position ◽  
Linear And Nonlinear

Linking pyrrole[3,2-b]pyrrole core with azulene moieties leads to dyes possessing strong visible light absorption, no emission, and a two-photon absorption spectrum.

Synthesis of π-extended B ← N coordinated phenanthroimidazole dimers and their linear and nonlinear optical properties

2020 ◽  
Vol 49 (23) ◽  
pp. 7737-7746
Author(s):  
Mukundam Vanga ◽  
Shreenibasa Sa ◽  
Anupa Kumari ◽  
Anna Chandrasekar Murali ◽  
Prakash Nayak ◽  
...  
Keyword(s):  
Optical Properties ◽  
Nonlinear Optical ◽  
Photon Absorption ◽  
Quantum Yields ◽  
Conjugation Length ◽  
Absorption Properties ◽  
Two Photon Absorption ◽  
Fluorescence Quantum Yields ◽  
Two Photon ◽  
Linear And Nonlinear

B ← N coordinated phenanthroimidazole dimers exhibit excellent fluorescence quantum yields in solution and conjugation length dependant two-photon-absorption properties.

scholarly journals Design principles and biological applications of red-emissive two-photon carbon dots

2021 ◽  
Vol 2 (1) ◽  
Author(s):  
Pooria Lesani ◽  
Aina Hazeera Mohamad Hadi ◽  
Zufu Lu ◽  
Stefano Palomba ◽  
Elizabeth J. New ◽  
...  
Keyword(s):  
Carbon Dots ◽  
Near Infrared ◽  
Water Solubility ◽  
High Water ◽  
Photon Absorption ◽  
Biological Applications ◽  
Two Photon Absorption ◽  
Two Photon ◽  
Current State ◽  
Wide Range

AbstractCarbon dots have been gaining attention in the field of nanobiotechnology due to their superior photostability, high water solubility, ease of synthesis and surface functionalization, chemical inertness, low toxicity, and excellent biocompatibility. They also exhibit good two-photon absorption and unique tunable optical properties across a wide range of wavelengths, from ultraviolet to near infrared endowing them with potential for a variety of biological applications. Recently, there has been a growing interest in the synthesis and development of red-emissive two-photon carbon dots. Here we present recent progress in the design requirements for red-emissive two-photon carbon dots, and review current state-of-the-art systems, covering their applications in bioimaging, biosensing, and photothermal and photodynamic therapy.

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