For this reason, the most common assemblies of electrostatically charged particles are branched chains.The global particle size analysis market size reached USD 355.9 Million in 2020 and is expected to register a CAGR of 5.2% during the forecast period. Spherical particles have the same curvature everywhere but once a dimer is formed, it can be approximated as a rod, and hence end-on addition of further particles is favored but not exclusively happening. Rod-shaped or oval particles, for this reason, would assemble end-on and form chains. This can be rationalized by the dependence of local field strength on curvature, which is maximal at points of maximal curvature. If the growth is due to electrostatic interactions, usually chain growth is observed. If the particles are not rigidly bound to each other this can also result in more densely packed spherical aggregates, which are thermodynamically favored due to minimizing interfacial energy. Pure diffusion-limited growth leads to fractal, dendritic 3-D structures. In fact, both quasi-one-dimensional (chains) and three-dimensional (dendritic structures and/or spheres) are observed in real systems. That being said, aggregates are still an incredibly way on predicting solid-state characteristics but they can be quite complicated. Finally something to note is that the aggregates may have slightly different environments on the molecular level due to how they are packed into these aggregates, this should mean that the lifetime of the aggregates is not a single value but a distribution of lifetime values. 1.) Some of you molecules are likely not aggregated due to aggregation equilibrium so you should see a lifetime consistent with individual molecules (if the aggregate particles don't change the mechanism/rate of quenching), additionally you may see two separate aggregate-based effects: Particles in aggregates may have longer lifetimes due to the fact that non-radiative decay rates may decrease, additionally if the aggregates can quench one another due to proximity you may see a short lifetime due to a new path (kq) competing. To elaborate on Peter's answer on aggregates, when you have aggregates there are several effects that can be present. See for example, many discussions on RG on this theme. Unless statistically valid numbers of particles can be taken, electron microscopy is not a route to particle size distribution determination but provide essential information as to the form of the particles, degree of aggregation, agglomeration, crystallinity versus amorphous nature and so on. In volume terms we'd look at the D - see attached where the mass or volume weighting is important. However, the 100 nm particle has a million times as much mass or volume and thus contains a million times as much value (a volume or mass distribution is equivalent to a $ distribution). So the 1 nm particle is equivalent to the 100 nm particle in mathematical terms for a number distribution. In a number distribution, every particle has equal relevance or weighting. Good luck.Įlectron microscopy provides a number distribution whereas DLS provides an intensity distribution. Also, Nanotoxicology, 2013 7(4):389 might be of use. You will have to test your material to determine if you can reach a size small enough to measure by DLS (a micron or less, generally). The primary crystallites are about 20 nm or smaller, but they are fused into small aggregates that are impossible to break up further under typical lab conditions. Application of high intensity direct sonication, for an appropriate time, and under appropriate solution conditions can break agglomerates down to a primary aggregate size of about 70-80 nm. Low energy dispersion in acidic water will generate a broad distribution of agglomerates and aggregates from a few hundred nm up to several micrometers. I disagree with the first response, in that it is entirely possible to disperse very small particles fully in suspension if sufficient energy is used, the solution chemistry is appropriate and the particles are not chemically fused together (i.e., aggregates vs. You need to know what the material is, roughly what the primary particle size is, and, if possible, what the isoelectric point is, unless you use surfactants for dispersion. There is no set procedure to accomplish your task. The attached protocol may be of some help.