['Whilst', 'a', 'number', 'of', 'techniques', 'have', 'been', 'employed', 'for', 'this', 'purpose', ',', 'it', 'is', 'clear', 'that', 'various', 'techniques', 'within', 'transmission', 'electron', 'microscopy', '(', 'TEM', ')', 'will', 'be', 'among', 'the', 'most', 'versatile', 'and', 'informative', 'for', 'this', 'purpose', ',', 'although', 'additional', 'information', 'can', 'be', 'added', 'by', 'techniques', 'such', 'as', 'atom', 'probe', 'tomography', '.']