Glass capillary optics for producing nanometer sized beams and its applications

We have developed a method to produce micro/nano meter sized beams of keV energy highly charged ions (HCIs) and MeV energy protons/He ions with tapered glass capillary optics for application of surface modifications and a biological tool called “cell surgery”, respectively. The transmission through the tapered glass capillaries with inlet diameter of 0.8 mmϕ, outlet diameter from 900 nmϕ to several tens of microns and length of about 50 mm was performed using 8/64 keV Ar8+ beams. The transmitted beams had a density enhancement of about 10 and were guided through a capillary tilted by as large as ±100 mrad. The charge state of the beams was kept during the transmission. The combination of MeV proton/He ion beams and the capillary with a thin end window at its outlet can realize pinpoint energy deposition and three-dimensional selection of the bombarding point in an arbitrary position of a living cell or in any liquid object. We demonstrated that a real biological cell, HeLa cell with the nucleus labeled by green fluorescent protein (GFP), was irradiated with the microbeam, which was prepared by 4 MeV He2+ entering a capillary with an end window of 7.3 μm in thickness and outlet diameter of 9.6 μmϕ. The transmitted MeV ion beams had density enhancement up to 1000 according to the capillary outlet sizes, which are applicable to various material analyses employing microbeams.

Research highlights
► Micro/nano meter sized ion beams are provided by tapered glass capillaries.
► Capillary’s inner radius was measured as a function of position along its axis.
► Density enhancement and guiding effect can be expected for keV ion beams.
► Combination of MeV ions and end windows has the possibility to realize cell surgery.
► Density enhancement of muon beams was also obtained by tapered insulator tubes.