Depth profiling of light elements using a nuclear microprobe

In this paper, we present some examples of depth profiling of light elements with a nuclear microprobe performed at LARN during the last decade. Some new possibilities of ion beam microanalysis of light elements with our 2 MV Tandetron accelerator are also discussed.

The first example of application consists of depth profiling of nitrogen and aluminium on a SiAl alloy implanted with nitrogen. The nuclear microprobe was used to determine three-dimensional distribution of aluminium, silicon and nitrogen in a specific grain of the implanted alloy. The nitrogen depth profile was measured using the well known 15N(p,αγ)12C nuclear resonant reaction at 429 keV. The aluminium depth profile was measured with the resonant nuclear reaction 27Al(p,γ)28Si at 991.8 keV.

Depth profiling of carbon and oxygen is also possible using nuclear reactions induced by 3He particles. Nuclear reactions like 12C(3He,pi)14N (i=0,1,2) or 16O(3He,α0)15O were used to measure local wear tracks on a diamond coating after a fretting test against a Cr steel ball.

PIXE microprobe and nuclear reactions induced by deuterons were also used to characterise the gold–silicon alloy formed by the diffusion of silicon into gold foils. The nuclear reaction 28Si(d,p)29Si in a transmission geometry was used in order to depth profile silicon especially in the grain boundaries of the gold–silicon alloy.

Some new perspectives of depth profiling light elements are also presented using our new 2 MV Tandetron accelerator, such as high energy 4He microbeams for depth profiling of carbon or nitrogen.