Wet SEM Analysis of Quantum dot emulsions - Rice University

Test run 2: The effect is the same as in Test run 1. If the electron beam is pointed in the
center of the Qdot emulsion the heat of beam causes bubbles. The gray background is the
surface of the Emulsion. Except for the bubbles which appeared on the surface of the emulsion
occasionally no detailed morphology of the emulsion or Aggregation of Qdots can be obtained
in this experimental set up. To download video (use Microsoft Media player) please go to we
blink:
Test run 3: To download video (use Microsoft Media player) please go to we blink:
No useful data could be obtained from Test run 1 & 2. In this experimental set up the electron
beam was pointed close to the edge of the stainless steel sample holder (see video). The edge
of the sample holder served as reference point to help visualize the emulsions Interface to the
holder. The following Pre-conditioning, Room temperature, Drying steps were applied to the
Blank/ control emulsion to develop optimal experimental conditions to visualize details of
Qdot Aggregation in the subsequent Test run 4.
Pre-conditioning: This step is necessary to ensure optimal humidity condition to preserve
In this phase the Interface between emulsion to the left of the video (gray background, bubbles)
and the sample Holder to the right (bright white area with ripples) can be clearly distinguished.
Room temp.: This is the desired Characterization condition (Room temp. and humidity) for
Analysis. In this phase violent bubbling (Popcorn effect) of the emulsion (left gray region) can
be observed probably caused by the heat of the electron beam as it scans along the Interface.
Zooming into the emulsion region revealed forming of the bubbles and the surface morphology
of the emulsion droplets turned from a smooth gray surface (observed in Test run 1 & 2) into a
“Strawberry” type shape. No details other than bubble forming could be obtained.
Drying: This step was performed to check if the dried form of the emulsion reveals more of
the emulsion details. Temperature decrease to 273 K= 0º C, ~ 100% Humidity, 2.44 Torr
Pressure. Apply Vacuum to dry sample. Morphology Analysis of emulsion. . In this phase
enhanced violent bubbling of the emulsion (left gray region) can be observed probably caused
by the vacuum and the heat of the electron beam as it scans along the Interface.
Room temp. The “dried emulsion” was put back on Room temperature to check emulsion
behavior. As the electron beam scans along the sample the “Strawberry” type of emulsion
droplets developed and additional micro bubbles on the surface of droplets. No details other
than additional bubble forming could be obtained.
Test run 4: To download video (use Microsoft Media player) please go to we blink:
The sample chamber conditions in Test run 3 were applied to the emulsion containing Qdots in
the hope that the different steps would visualize Qdots and Aggregation of Qdots in the
emulsion.
Pre-conditioning: This step is necessary to ensure optimal humidity condition to preserve
In this phase the Interface between emulsion to the left of the video (gray Background,
bubbles) and the sample Holder to the right (bright white area with ripples) can be clearly
distinguished.
Room temp.: This phase is the desired Characterization condition (Room temp. and humidity)
for Analysis. Much less bubbling (Popcorn effect) of the emulsion (left gray region). More like
a “Moon surface visual effect” can be observed probably caused by the heat of the electron
beam as it scans along the Interface. Zooming into the emulsion region revealed forming of