Pd nanoparticles formation by femtosecond laser irradiation and the nonlinear optical properties at 532 nm using nanosecond laser pulses

Journal Article · Sat Jan 15 04:00:00 EST 2011 · Journal of Applied Physics

DOI:https://doi.org/10.1063/1.3533738· OSTI ID:21538043

Guanghua, Fan; Shiliang, Qu; Qiang, Wang ^[1]; Chongjun, Zhao ^[2]; Lei, Zhang; Zhongguo, Li ^[3]

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1. Department of Optoelectronics Science, Harbin Institute of Technology at Weihai, Weihai 264209 (China)
2. Key Laboratory for Ultrafine Materials of Ministry of Education, School of Materials Science and Engineering, East China University of Science and Technology, Shanghai 200237 (China)
3. School of Physical Science and Technology, Suzhou University, Suzhou 215006 (China)

Pd nanoparticles (NPs) were prepared by focused femtosecond laser irradiation of PdCl{sub 2} dissolved in ethanol. Transmission electron microscopy (TEM) analysis revealed that Pd NPs show certain crystalline microstructure, and the average diameter is 3.4 nm with narrow size distribution from 2.0 to 6.0 nm. The nonlinear optical absorption and refraction of Pd NPs solution were investigated with nanosecond laser pulses at 532 nm. The nonlinear absorption of Pd NPs is saturable at low intensity of 3.28x10{sup 11} W/m{sup 2} but it is changed to reverse saturable with the intensity increased to 7.96x10{sup 11} W/m{sup 2}, which accordingly indicates the nonlinear refraction is changed from self-defocusing to self-focusing. The transition of the nonlinear absorption with the increase in pulse intensity is analyzed by an empirical model which includes mostly saturable absorption (SA) and two-photon absorption (TPA). The intensity of saturable I{sub s} is obtained, along with TPA coefficient {beta}. SA and TPA are both originated from the interband transition between the d band and s-p conduction band. The SA possess less occupied density of states in the ground state and less unoccupied density of states in the excited state than that of TPA, so the TPA dominates the nonlinear absorption when the pulse intensity is high, leading to as-observed transition from SA to TPA. The refraction variation with increase in pulse intensity is attributed to the interband transition of electrons from d band to s-p conduction band in the Pd NPs.

• OSTI ID: 21538043
• Journal Information: Journal of Applied Physics, Journal Name: Journal of Applied Physics Journal Issue: 2 Vol. 109; ISSN JAPIAU; ISSN 0021-8979
• Country of Publication: United States
• Language: English

Related Subjects

77 NANOSCIENCE AND NANOTECHNOLOGY
ABSORPTION
BEAMS
BOSONS
CHLORIDES
CHLORINE COMPOUNDS
DENSITY
DISTRIBUTION
ELECTROMAGNETIC RADIATION
ELECTRON MICROSCOPY
ELECTRONS
ELEMENTARY PARTICLES
ELEMENTS
ENERGY LEVELS
ENERGY-LEVEL TRANSITIONS
FABRICATION
FERMIONS
GROUND STATES
HALIDES
HALOGEN COMPOUNDS
LASER RADIATION
LEPTONS
MASSLESS PARTICLES
METALS
MICROSCOPY
MICROSTRUCTURE
MULTI-PHOTON PROCESSES
NANOSTRUCTURES
OPTICAL PROPERTIES
PALLADIUM
PALLADIUM CHLORIDES
PALLADIUM COMPOUNDS
PARTICLE SIZE
PHOTONS
PHYSICAL PROPERTIES
PLATINUM METALS
PULSES
RADIATIONS
REFRACTION
SIZE
SORPTION
TRANSITION ELEMENT COMPOUNDS
TRANSITION ELEMENTS
TRANSMISSION ELECTRON MICROSCOPY