Force XmlDocument to save empty elements with an explicit closing tag

I have the following code:

string PathName = "C:\\Users\\TestUser\\Documents\\Project";
string FileName = "settings.xml";

XmlDocument Settings = new XmlDocument(); 
Settings.Load(Path.Combine(PathName, FileName));

XmlNode KnowledgeNode = Settings.SelectSingleNode("/Config/Map/Knowledge");

XmlNode UsersNode = Settings.CreateNode(XmlNodeType.Element, "Users", null);
XmlAttribute FileDirectory = Settings.CreateAttribute("FileDirectory");
FileDirectory.Value = UserSelectedFileDirectory;
UsersNode.Attributes.Append(FileDirectory);
KnowledgeNode.AppendChild(UsersNode);

Settings.Save(Path.Combine(PathName, FileName));

This results in my XML file containing <Users FileDirectory="C:\data" /> instead of <Users FileDirectory="C:\data" ></Users> as I want.

How do I create the end element? I've given it a Google and I can't find much. Any help is appreciated, thanks.