High concentrations of defects are introduced into nanoscale ZnO through non‐equilibrium processes and resultant blue emissions are comprehensively analyzed, focusing on defect origins and broad controls. Some ZnO nanoparticles exhibit very strong blue emissions, the intensity of which first increase and then decrease with annealing. These visible emissions exhibit strong and interesting excitation dependences: 1) the optimal excitation energy for blue emissions is near the bandgap energy, but the effective excitation can obviously be lower, even 420 nm (2.95 eV < Eg = 3.26 eV); in contrast, green emissions can be excited only by energies larger than the bandgap energy; and, 2) there are several fixed emitting wavelengths at 415, 440, 455 and 488 nm in the blue wave band, which exhibit considerable stability in different excitation and annealing conditions. Mechanisms for blue emissions from ZnO are proposed with interstitial‐zinc‐related defect levels as initial states. EPR spectra reveal the predominance of interstitial zinc in as‐prepared samples, and the evolutions of coexisting interstitial zinc and oxygen vacancies with annealing. Furthermore, good controllability of visible emissions is achieved, including the co‐emission of blue and green emissions and peak adjustment from blue to yellow.

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Mass spectrometry in conjunction with atmospheric pressure ionization methods enables the in vivo investigation of biochemical changes with high specificity and sensitivity. Laser ablation electrospray ionization (LAESI) is a recently introduced ambient ionization method suited for the analysis of biological samples with sufficient water content. With LAESI mass spectrometric analysis of chimeric Aphelandra squarrosa leaf tissue, we identify the metabolites characteristic for the green and yellow sectors of variegation. Significant parts of the related biosynthetic pathways (e.g., kaempferol biosynthesis) are ascertained from the detected metabolites and metabolomic databases. Scanning electron microscopy of the ablated areas indicates the feasibility of both two-dimensional imaging and depth profiling with a approximately 350 microm lateral and approximately 50 microm depth resolution. Molecular distributions of some endogenous metabolites show chemical contrast between the sectors of variegation and quantitative changes as the ablation reaches the epidermal and mesophyll layers. Our results demonstrate that LAESI mass spectrometry opens a new way for ambient molecular imaging and depth profiling of metabolites in biological tissues and live organisms.

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