Research

Online thermal desorption aerosol mass spectrometers (TDAMS) provide useful insights into the sources and formation processes of ambient aerosols. TDAMS instruments generally use a two-step detection scheme: aerosol particles are first collected and vaporized by thermochemical processes in a vacuum chamber, following which the evolved gaseous compounds are ionized and then detected. We have developed a new particle mass spectrometer (rTDMS) to separately quantify the mass concentrations of non-refractory and refractory sulfate compounds1. A cup-shaped graphite collector coupled with a focused CO2 laser enables high desorption temperature (~1200 K). Laboratory experiments have demonstrated that the rTDMS can detect ion signals originating from refractory sulfate aerosols including K2SO4, Na2SO4, and MgSO4 (Fig. 1). ...

Particle emissions from turbofan engines, which are commonly used in civil aviation, include the formation of non-volatile particles (mainly soot) during combustion processes and the nucleation and growth of volatile particles (mainly sulfate and organics) during plume expansion. We conducted field measurements of aerosols near a runway at Narita International Airport (NRT) in cooperation with National Institute for Environmental Studies. Our measurements have provided new insights into the characteristics of sub-10 nm particle emissions from in-use aircraft and the significance of jet engine lubrication oil as a source of aircraft exhaust ultrafine particles (UFPs) at 10–30 nm1, 2. ...

The atmosphere-ocean system contains diverse particulate matter including mineral particles from deserts, sea salt particles from ocean surfaces, carbonaceous particles from forest fires, anthropogenic particles from fossil fuel combustion, biological particles (marine microorganisms), and fragmented microplastic particles. Quantitative understanding of their physicochemical properties, dynamics, and spatiotemporal distributions requires in-situ observations and sampling measurements. Selection of observation methods involves balancing data quality/quantity with analytical efficiency, necessitating optimization or development of methods tailored to research objectives. ...

Black carbon (BC) in the atmosphere is a carbonaceous particulate matter produced by fossil fuel combustion and wild fires. As the strongest light-absorbing aerosol component, BC significantly influences global temperature, atmospheric circulation, and precipitation through direct atmospheric heating and reduction of snow/ice surface albedo. However, the complex refractive index—a key optical property of solid materials—remained undetermined for atmospheric BC for many years1. The imaginary part of the complex refractive index crucially affects the particle’s light absorption efficiency. ...

Optical particle sensors (such as Complex Amplitude Sensing: CAS) require theoretical calculations of light scattering for physical interpretation of measurement data. These calculations aim to predict the amplitude and phase of scattered field at a specific detector configuration using input parameters (particle parameters: shape, complex refractive index, volume, mixing state; incident field parameters: frequency, medium refractive index, polarization state, beam shape). Exact scattering solutions exist only under limited conditions like spherical particles, necessitating numerically solving Maxwell’s equations for most practical applications. While various numerical methods1 and associated open-source/commercial software are available, cutting-edge research often requires custom software. ...