Using $scope and 'this' in the controller with Angular UI Router

Regarding $scope and this when using ui-router,

If I am using the controllerAs syntax, ie:

.config(['$stateProvider', function($stateProvider) {
    $stateProvider
        .state('app.login', {
            url: '/login',                  
            templateUrl: 'modules/login/login.html',
            controllerAs: 'login',
            controller: 'LoginCtrl',
            data: {
                authorizedRoles: [USER_ROLES.all]
            }
        });
}])

In my controller then, I'm using this instead of $scope. So I have code like this in my login controller:

this.func1 = func1;
this.func2 = func2;
this.message = "Hello world!";

But I'm also using $scope to listen to globally broadcasted events from my $rootScope, because if I remember correctly, this doesn't have methods belonging to $scope, even though they are being interchanged.

$scope.$on('event', handler);

So I'm listening to an event broadcast by $rootScope and calling some other controller logic, like func2, when this event is broadcasted:

$scope.$on('auth-login-failed', function(event) {
// call some other function in controller
});

What if I wanted to call func2 inside the $on handler? Should I do some convention where I initialize something like this in my controller?

var that = this;

$scope.$on('auth-login-failed', function(event) {
    this.func2();
});

I'm just curious on the best way to proceed and what the general convention is here. Is it proper to use both $scope and this, and what are the main differences between the two, since they can be interchanged?