Direct Observation of Langmuir Films of C₆₀ and C₇₀ Using Brewster Angle Microscopy

Abstract

The aim of this paper is to present a direct observation of Langmuir films made of C 60 and C 70 along the process of their compression at 298 K, using Brewster angle microscopy. We found coexisting a gas phase and a condensed phase at low area densities. Our results agree with the formation of multilayers even at low area densities (500-1000 Å 2 /molecule). We made compressions of the films at several speeds. Using dilute spreading solutions (∼1 × 10 -5 M) and slow compressions we obtained multilayers. With rapid compressions, we found that the condensed phase formed beautiful foamlike structures and circular domains of different sizes at very low area densities. The circular domains developed holes (gas bubbles). As the compression of the films proceeded, those domains did not coalesce easily. Instead, the films prefer to form multilayers. Using concentrated spreading solutions (>1 × 10 -4 M) and slow compressions, multilayers were formed just after the deposition of the sample.

Preparation and characterization of electrically conducting Langmuir–Blodgett films of poly(N-octadecylaniline)

“…In monolayer formation the speeds of compression is an important parameter. At higher speeds, isotherms suffer from kinetic effects, which are related to the nucleation of the condensed phases and to the difficulty with which the condensed phase domains coalesce [18]. To check this, the isotherms were recorded at different barrier speeds (25, 50, 100, 150, 200, and 250 cm 2 min −1 ).…”

Physicochemical Study of Viral Nanoparticles at the Air/Water Interface

“…Langmuir monolayers have been widely studied since the early 1900s; most of the studies where done with lipids such as fatty acids, phospholipids, and cholesterol. − Classical Langmuir monolayers are characterized by amphiphilic molecules where a hydrophilic “head” was attached to a hydrophobic “tail” and the interactions between molecules were relatively easy to study. − Until now, many more systems such as proteins, carbon nanotubes, − and fullerenes have been studied at the air/water interface. However, larger biological samples have shown to be quite difficult to study mainly for the complexity of their interactions.…”

Nanoaggregates in floating layers of azaporphyrins

“…In the traditional one the structure of a layer is estimated from the surface area per molecule while extrapolating to zero surface pressure. In practice this value is determined from the intersection point of a straight line, whose segment approximates some part of a π-A-isotherm, and the A axis [13][14][15][16][17][18]. Such an approach gives only a qualitative estimation of state of a layer on a water surface.…”