Figure 5.

A scheme of the alternate growth mechanism. <a onClick="popup('http://www.nanoscalereslett.com/content/6/1/12/mathml/M2','MathML',630,470);return false;" target="_blank" href="http://www.nanoscalereslett.com/content/6/1/12/mathml/M2">View MathML</a> is the direction perpendicular to (10<a onClick="popup('http://www.nanoscalereslett.com/content/6/1/12/mathml/M1','MathML',630,470);return false;" target="_blank" href="http://www.nanoscalereslett.com/content/6/1/12/mathml/M1">View MathML</a>3) and <a onClick="popup('http://www.nanoscalereslett.com/content/6/1/12/mathml/M3','MathML',630,470);return false;" target="_blank" href="http://www.nanoscalereslett.com/content/6/1/12/mathml/M3">View MathML</a> is perpendicular to (0001). The theoretical angle (α1,2,3) between the trunk and its branches is 31.65°.

Yang et al. Nanoscale Res Lett 2011 6:12   doi:10.1007/s11671-010-9745-4