10:45 AM - 11:00 AM
[MIS07-01] Molecular-level understanding of ice crystal surfaces by advanced optical microscopy
Keywords:Ice, Surface melting, Quasi-liquid layer, Molecular step
Ice is one of the most abundant crystals on the earth, and hence the molecular-level understanding of ice crystal surfaces holds the key to unlocking the secrets of a number of fields. We and Olympus Engineering Co., Ltd. have developed laser confocal microscopy combined with differential interference contrast microscopy (LCM-DIM), by which we succeeded in the direct visualization of 0.37-nm-thick elementary steps [1] on ice for the first time with enough spatial and temporal resolution. Subsequently, the direct observations of spiral steps on ice basal faces revealed the double-spiral-step structure [2], the migration distance of water molecules adsorbed on a terrace [3], and the temperature dependence of the step kinetic coefficient [4].
On the other hand, we could also visualize the quasi-liquid layers (QLLs) on ice crystal surfaces [5], which are covered with thin liquid layers even below the melting point (0°C). The direct observations of QLLs revealed the appearance of two types of QLLs with different morphologies [5,6], the appearance temperatures and partial pressure of water vapor [6-8], the inducement of the formation of QLLs by strain [9], and the characteristic velocities of QLLs [10]. Further details of QLLs will be presented in "A-CC28: Glaciology" sessions.
In addition, we also found that atmospheric acidic gas (hydrogen chloride gas) strongly induced the appearances of droplets on ice surfaces (further details will be presented in "A-AS06: Atmospheric Chemistry" session). The droplets were observed in the temperature range of -15.0 ~ -1.5°C, where no QLL appears in the absence of HCl gas [11]. The HCl induced droplets were embedded into ice crystals by growth of ice crystals [12]. These results show the possibility that ice crystals can store large amount of gas components as fluid inclusions.
[1] Sazaki et al. (2010) PNAS 107, 19702.
[2] Sazaki et al. (2014) Cryst. Growth Des. 14, 2133.
[3] Asakawa et al. (2014) Cryst. Growth Des. 14, 3210.
[4] Inomata et al. (2018) Cryst. Growth Des. 18, 786.
[5] Sazaki et al. (2012) PNAS 109, 1052.
[6] Murata et al. (2016) PNAS 113, E6741.
[7] Asakawa et al. (2015) Cryst. Growth Des. 15, 3339.
[8] Asakawa et al. (2015) PNAS 113, 1749.
[9] Sazaki et al. (2013) Cryst. Growth Des. 13, 1761.
[10] Murata et al. (2015) Phys. Rev. Lett. 115, 256103.
[11] Nagashima et al. (2016) Cryst. Growth Des. 16, 2225.
[12] Nagashima et al., submitted.
On the other hand, we could also visualize the quasi-liquid layers (QLLs) on ice crystal surfaces [5], which are covered with thin liquid layers even below the melting point (0°C). The direct observations of QLLs revealed the appearance of two types of QLLs with different morphologies [5,6], the appearance temperatures and partial pressure of water vapor [6-8], the inducement of the formation of QLLs by strain [9], and the characteristic velocities of QLLs [10]. Further details of QLLs will be presented in "A-CC28: Glaciology" sessions.
In addition, we also found that atmospheric acidic gas (hydrogen chloride gas) strongly induced the appearances of droplets on ice surfaces (further details will be presented in "A-AS06: Atmospheric Chemistry" session). The droplets were observed in the temperature range of -15.0 ~ -1.5°C, where no QLL appears in the absence of HCl gas [11]. The HCl induced droplets were embedded into ice crystals by growth of ice crystals [12]. These results show the possibility that ice crystals can store large amount of gas components as fluid inclusions.
[1] Sazaki et al. (2010) PNAS 107, 19702.
[2] Sazaki et al. (2014) Cryst. Growth Des. 14, 2133.
[3] Asakawa et al. (2014) Cryst. Growth Des. 14, 3210.
[4] Inomata et al. (2018) Cryst. Growth Des. 18, 786.
[5] Sazaki et al. (2012) PNAS 109, 1052.
[6] Murata et al. (2016) PNAS 113, E6741.
[7] Asakawa et al. (2015) Cryst. Growth Des. 15, 3339.
[8] Asakawa et al. (2015) PNAS 113, 1749.
[9] Sazaki et al. (2013) Cryst. Growth Des. 13, 1761.
[10] Murata et al. (2015) Phys. Rev. Lett. 115, 256103.
[11] Nagashima et al. (2016) Cryst. Growth Des. 16, 2225.
[12] Nagashima et al., submitted.