Kyushu University · Engineering
Professor Masaharu Shiratani's research lab specializes in plasma science and engineering, with a focus on non-thermal plasma applications in agriculture, nanoparticle growth dynamics in reactive plasmas, and the development of plasma-based nano-fabrication systems. The lab investigates the effects of plasma and plasma-treated water on seed germination and plant growth, while also conducting fundamental studies on the formation, size distribution, and transport of nanoscale particles in silane and helium-diluted silane plasmas. A key innovation from the lab is the concept of a 'nano-factory in plasma,' where plasma is used to synthesize, transport, and assemble nanoblocks into ordered structures on substrates, enabling precise control over nanomaterial synthesis. The lab combines advanced optical diagnostics, such as laser-light scattering and electron microscopy, to understand and manipulate nanoscale processes in real time.
Figures are computed from collected data and may differ slightly.
In recent years, non-thermal plasma (NTP) application in agriculture is rapidly increasing. Many published articles and reviews in the literature are focus on the post-harvest use of plasma in agriculture. However, the pre-harvest application of plasma still in its early stage. Therefore, in this review, we covered the effect of NTP and plasma-treated water (PTW) on seed germination and growth enhancement. Further, we will discuss the change in biochemical analysis, e.g., the variation in phytoh
A polarization-sensitive laser-light-scattering method is developed for simultaneous in situ measurements of properties (size, size dispersion, density, and refractive index) of particulates formed in processing plasmas. The developed system is applied to observe the growth processes of particulates in a range of their size larger than about 10 nm in rf silane plasmas. A size, a size dispersion (logarithm of a standard deviation of size), a density, and a refractive index of particulates in the
The effects of gas temperature gradient, pulse discharge modulation, and hydrogen dilution on the growth of particles below about 10 nm in size in silane parallel-plate RF discharges are studied using a high-sensitivity photon-counting laser-light-scattering (PCLLS) method. Thermophoretic force due to the gas temperature gradient between the electrodes drives neutral particles above a few nm in size toward the cool RF electrode which is at room temperature. Pulse discharge modulation is much mor
Growth kinetics of particles above 10 nm in size in silane RF discharges has been extensively studied and fairly well clarified. Moreover, recent developments of new measurement methods for particles below 10 nm in size have led to a rapid advance in understanding the growth processes of small particles. Such previous studies are reviewed with the accent on their initial growth phase corresponding to a particle size range below 10 nm. The notable effect of pulse modulation of the RF discharges o
Size, density, and morphology of particulates in helium-diluted silane rf plasmas are studied using a scanning electron microscopic method. The experimental results show that particulates grow through three phases of nucleation, rapid growth, and growth saturation. Particulates in two different size ranges coexist after the initiation of the rapid growth phase, the size distribution of particulates in each size group is found to be well expressed by both the lognormal and normal distributions wi
We propose the concept of ‘nano-factory in plasma’ which is a miniature version of a macroscopic conventional factory. A nano-factory in plasma produces nanoblocks and radicals (adhesives) in reactive plasmas, transports nanoblocks towards a substrate and arranges them on the substrate. We describe several key control methods for a nano-factory in plasma: size and structure control of nanoparticles, control of their agglomeration, transport and sticking, and then explain the combination of sever
The surface loss probability β of CH 3 radicals on a-C:H surface is determined by time-resolved threshold ionization mass spectrometry in pulsed RF discharges. In the post-discharge, the β value decreases from 0.011–0.015 to 0.001–0.002 in about 10 ms. This time evolution suggests that the loss probability depends on incoming ion and radical fluxes on the surface. We present a simple model of the surface reaction kinetics in which the number of active chemisorption sites on the surface is determ
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