Nanoplasmon‐Nanoplasma Transition in Cu Nanoparticle: Distinction of Electron Emission

Abstract

The electron response of nanoplasmon and nanoplasma in the laser field is greatly important for improving the functionality and efficiency of many potential applications. However, how and under what conditions the nanoplasmon‐nanoplasma transition works remains poorly understood due to radiation damage and charge buildup. Utilizing the combined aerodynamic lens and velocity map imaging spectrometer, this transition mediated by different mechanisms are demonstrated, as verified by the distinct photoelectron momentum distributions from Cu nanoparticles. Initially the polarization‐dependent distributions emphasize the domination of surface emission driven by the plasmonic field. Subsequently the transition starts and the competition of volume‐multiphoton and thermionic emission plays the intermediate state dominating the transition process. Finally, a complete plasma is generated with the leading role of thermionic emission, which is confirmed by first observing the correlated electronic decay in metal nanoparticles. These findings bridge the gap between electron emission in nanoplasmonic and nanoplasma states and identify the mechanism‐specific contributions, which will offer general principles for designing nanostructure and laser fields to control electron excitation and emission in practice.

Super‐White Boron Nitride Aerogel‐Enabled High‐Energy Laser Irradiation Protection

“…Notably, the laser spot of laser equipment can reach 30 cm, in which case the laser power density will be lower. [10,27,28] Additionally, the typical laser damage threshold for a flight vehicle shell [28] is approximately 10 3 W cm −2 . The above analysis indicates that the Laser protection threshold and density of the BN aerogel compared to other previously reported materials e), including a tantalum disilicide and zirconium disilicide-modified carbon fabric-reinforced phenolic composite (TaSi 2 /ZrSi 2 /C-Ph), graphite/SiO 2 (G/SiO 2 ), plasma-sprayed La 1-x Sr x TiO 3+𝛿 coating (LST), glass fiber-reinforced bisphenol-A based polybenzoxazine composites (GF/BAA), zirconium diboride particulates and silicon carbide whiskers with zirconia composite coating (ZrO 2 /ZrB 2 /SiC), zirconium carbide-modified short-carbon-fiber-reinforced phenolic-resin (ZrC/CF/BPF).…”

“…The power of high-energy laser equipment is reported to be ≈10-100 kW. [10,27] If the diameter (2R) of the circular laser spot was approximately 10 cm, the power (P) and laser power density (P d ) were 100 kW and ≈1.27 × 10 3 W cm −2 , respectively (P d = P/𝜋R 2 = 100 000 W/(3.14 × 5 cm × 5 cm)). Notably, the laser spot of laser equipment can reach 30 cm, in which case the laser power density will be lower.…”