We present results from a high-angular-resolution survey of 78 very low mass ( VLM ) binary systems with 6.0 \leq V-K colour \leq 7.5 and proper motion \geq 0.15 arcsec/yr .
Twenty-one VLM binaries were detected , 13 of them new discoveries .
The new binary systems range in separation between 0.18 arcsec and 1.3 arcsec .
The distance-corrected binary fraction is 13.5 ^ { +6.5 } _ { -4 } % , in agreement with previous results .
Nine of the new binary systems have orbital radii > 10 AU , including a new wide VLM binary with 27 AU projected orbital separation .
One of the new systems forms two components of a 2300 AU separation triple system .
We find that the orbital radius distribution of the binaries with V-K < 6.5 in this survey appears to be different from that of redder ( lower-mass ) objects , suggesting a possible rapid change in the orbital radius distribution at around the M5 spectral type .
The target sample was also selected to investigate X-ray activity among VLM binaries .
There is no detectable correlation between excess X-Ray emission and the frequency and binary properties of the VLM systems .